Stormtroopers have evolved considerably over the course of the current Star Wars canon, but because of how the parts of the story has been released, the evolution is not strictly linear. While within the story, the armour has gotten better, the constraints of the time during which the movies were produced is visibly telling. For example, the knee guards of the stormtroopers went from being flexible in the prequel trilogy, to being rigid or non existent in the original trilogy, and back to being flexible in the sequel trilogy.
Essentially, there are three variants of the stormtroopers in the three trilogies. In Episodes I, II and III, the stormtroopers are clone troopers. These are all soldiers cloned from a single individual, Jango Fett. Initially, the clones were produced only on Kamino. The Kaminoans specialised in cloning technologies, but later on the clones were grown on other worlds as well. The clone troopers obeyed the Jedi commanders, but they actually served the Republic Chancellor, Palpatine. Palpatine would eventually make the clone troopers kill their Jedi Generals.
After the execution of order 66, the stormtroopers served the Galactic Republic, and became known as the Imperial stormtroopers. During this period, the original clone troopers started dying off because of they aged at twice the rate of normal humans. The clones were gradually replaced with regular citizens from the galaxy, who were indoctrinated into unquestionable loyalty to Emperor Palpatine from a very young age. They also went through a gruelling training regime.
Once Emperor Palpatine was defeated, The First Order rose from the ashes of the Empire. The stormtroopers then began to serve The First Order, and their numbers were maintained by abducting children. The armour of the First Order stormtroopers was upgraded, and they were given newer weapons for more specialised roles. Apart from the equipment, the training methods was also changed by the First Order. The First Order training regime is a more well rounded approach, with a focus on improvisation and guerrilla tactics. Through most of the history of stormtroopers, their only official personal identifications are serial numbers. Under the Jedi and some forward thinking officers however, Clone Commanders were given personalised names.
Clone troopers, Imperial stormtroopers and First Order stormtroopers neatly coincide with the three Star Wars trilogies.
The basic armour of the stormtroopers have remained essentially the same from their inception. The armour is inspired by the armour of the Mandalorian Shocktrooper supercommandos. Jango Fett provided consultation for the design of the armour, but the blunt design also shows Kaminoan influence. The Kaminoans could see only in the ultraviolet range, which is why the original Clone trooper armour was stark white. The armour lasts practically indefinitely, and local civilians are known to re-purpose parts of the armour scavenged from battlefields for their own uses.
The white armoured shell covered a pressurised black body glove. The body glove, along with a life support system in the backplate offered protection for brief durations even in the vacuum of space. The body glove also provided thermal regulation to the troopers. A space backpack with a longer life support duration allowed the troopers to execute longer missions in free space.
The armour plates themselves improved over the course of the movies. The clone troopers used a plastoid-alloy composite, the Imperial stormtroopers had a plastoid composite armour, while the First Order stormtroopers used composite betaplast plating. Magnatomic gription panels lining the inside of the armoured plates allowed the pieces to be attached to the underlying body glove. Republic Commandos used superior Katarn armour, which provided better protection than the standard armour, but was much more expensive.
An interesting aspect of the armour is how the knee plates evolved. Initially, they were attached to both legs and were flexible. The Imperial troopers had no knee plate on the left leg, but the right leg had a shield to protect the trooper when assuming a sniping position. The left leg had additional batteries for the suit systems. The First Order stormtroopers had flexible knee joints, which improved mobility. The First Order Flametroopers had integrated knee plates. The knee plates of stormtroopers were a weak point, and were in need of frequent replacement.
One of the most noticeable differences between stormtroopers are the changes in the helmets. The Clone troopers had a T shaped helmet, which was close to the original Mandalorian design. The Imperial troopers used a more threatening design, with small eye holes, and the air filtering systems separated. The First Order stormtroopers used a design where the visor was again fused together and flowed around a nose plate. The air filtration systems were moved to both the sides of the helmet.
A variety of helmets were issued to the troopers depending on the needs. All the troopers had integrated communication systems within their helmets. The helmets invariably had an air filtration system of some sort, to process the air of various atmospheres. The Clone troopers had basic polarised lenses, but advanced imaging systems were introduced over time. The Katarn helmets had tactical overlays on the visors. Imperial troopers could use sophisticated visors that provided visual overlays of the surrounding terrain. If there was darkness, or smoke in the environment, the surroundings could be holographically projected on the visors. First Order stormtroopers mostly did away with any visual enhancement in their visors to keep the weight down. Instead, they were equipped with quadnoculars.
Captain Phasma had a unique chromium coated armour that was primarily an indication of her status. The finish was useful for deflecting harmful radiation. The chromium itself was salvaged from Emperor Palpatine’s Naboo yacht. The custom blaster issued to Phasma was also plated with the same chromium armour.
Although the Clone troopers were initially were given all white armour, they were upgraded with colours to tell legions and specialised troopers apart. Among the earliest specialised troopers were the shock troopers, who were deployed on Coruscant to patrol public areas and keep the citizens in line. The troopers deployed to jungle planets had camouflaged armour. Clone Pilots were another specialised branch, who were trained to fly starfighters. Other troopers were specialised to use all terrain vehicles, speeder bikes and jetpacks. There were even Clone trooper hackers, or Slicers. Republic Commandos were specialised troopers with their own armour. Advanced Recon Commandos or ARCs were deployed for specialist missions, and were personally trained by Jango Fett. The ARCs were equipped with enhanced air filters, or even integrated oxygen supplies in their helmets.
The stormtroopers became even more specialised in the Imperial era. Snowtroopers were equipped to handle extremely cold environments such as Hoth. They had ice boots, heated pants, and enough supplies to survive for two weeks in frozen environments without any additional support. The Magma troopers could operate as easily on volcanic worlds with an excess of lava. Scout troopers had larger than usual visors that were equipped with night vision, motion detectors and target magnification. The Scout troopers rode on Speeder Bikes and were equipped with their own unique blasters. Trooper divisions could also be airborne, operate underwater, or tunnel through the ground. Death troopers with an intimidating black armour were used as bodyguards for VIPs.
The First Order Flametroopers, had backpacks with propellants. They were used torch the cover of enemies, and at the same time provide cover for the stormtroopers. They could create walls of fiery infernos, through which the stormtroopers could themselves safely pass through. Flametroopers could also be used to flush out enemies from trenches, who would then be attacked by the regular stormtroopers. Their helmets had extremely narrow slits to reduce glare from the torching equipment, as well as special linkages for a supplemental breathing tank.
Another variant introduced by the First Order, were riot control stormtroopers. The troopers were equipped with betaplast ballistic riot control shields, and an electric riot control baton. The batons were wielded like tonfas, and could stand up to lightsabers as well. In case the situation escalated, the riot control troopers were equipped with blasters, and were authorised to use lethal force when required. First Order Snowtroopers had improved helmets and better protection against with a wind resistant oversuit.
All troopers were equipped with a utility belt that contained additional magazines and survival equipment. The clone troopers had a grappling hook housed within the utility belt. The utility belts of Imperial stormtroopers had the usual survival supplies and grappling hooks that the Clone troopers were equipped with. Additionally, they also had a comlink and a thermal detonator. The comlinks provided increased range. Usually, a trooper was issued with just one thermal detonator for a mission. The detonators could be timed or remotely detonated. The controls were all white so that they could not be operated by anyone else. The backpacks could be equipped with life support systems, mortar launchers, communication equipment and gear for establishing a security perimeter.
While the clone troopers were equipped with DC-15 Blasters, the Shocktroopers were equipped with DC-15 rifles. The rifles had a sniper scope that doubled as a grip. These were both plasma based weapons that used electromagnets to accelerate small amounts of gas. The plasma rifles ionized tibanna gas stored in cartridges. Each cartridge could provide up to 500 rounds. High ranking commanders and ARC troopers used DC-17 blasters, which were a sidearm that provided a capacity of 50 shots.
Imperial era stormtroopers used a short range combat pistol, which had a scope for some reason. The Imperial stormtroopers used the E-11 BlasTech blaster, which had a similar mechanism to the DC-15 blasters. Even the blasters were equipped with a permanent scope on top. The Imperial stormtroopers used the BlasTech DLT 20A Laser Rifle. The First Order stormtroopers used the Megablaster or the Sonn-Blas FWMB-10 repeating blaster as their primary weapon. The sidearm was a Sonn-Blas SE-44C, with a vibrating grip to alert the trooper of low ammunition. The scoped rifle issued to First Order stormtroopers was the Sonn-Blas F11D. The flametroopers were issued with a D-C93 Incinerator, which had back mounted propellant tanks, and D-93w flame projector gun. The riot control troopers used the Z6 baton.
The Clone Troopers used a variety of speeders towards the end of the Clone Wars. The Swamp Speeders could seat two, was equipped with a turbofan engine on the back, laser scanners beneath the chassis and blasters in the front. The more streamlined BARC speeder had a repulsorlift engine.
In the Imperial era, the speeder bikes was the ubiquitous transport of the scout troopers. These bikes were driven by repulsorlift engines, and were highly maneuverable even at extreme speeds. The repulsor drive was located at the back, while vanes on the front provided a guided repulsor field. A sensor at the top of the vehicle was used for scanning the terrain ahead.
Clone Troopers also used the AT-RT walkers, or the All Terrain Recon Transport. They were smaller than the well known AT-ST walkers from the Imperial period, with an open cockpit and a front facing repeating blaster. The Pod walker had three feet, a laser canon as well as a blaster cannon. The All Terrain Tactical Enforcer was a walking tank with six legs. It was equipped with six laser cannon turrets along the sides, and a mass driver cannon on top.
Troopers had a number of walkers in the Imperial Era. The most famous ones are the All Terrain Armored Transport (AT-AT) walker and the All Terrain Scout Transport (AT-ST) walker. The AT-AT walkers were large, dominating presence on battlefields. They were supported by the smaller AT-ST walkers. The First Order used an upgraded version of the AT-AT walker known as the All Terrain MegaCaliber Six (AT-M6) walker, which had gorilla like forelegs.
For transport and deployment purposes, the Clones used Republic gunships. These could house upto 30 troopers at a time, who would jump out of the sides. The wings had laser turrets. The AT-TE walkers could be mounted under a Republic gunship for battlefield deployment.
In the Imperial era, troopers were deployed using two types of shuttles. The Lambda-class T-4a shuttle had the iconic tri-wing design, and could ferry up to 20 troopers at a time. The larger Sentinel class shuttle could carry a staggering 75 troopers at a time. To rapidly deploy all the troopers on board, the Sentinel class shuttles had ramps in the front and back, as well as doors on the sides.
The First Order troopers used the Troop Transporter that ferried 20 troopers, or two squads at a time. These two squads would line up to the left and right side of the ship. A disembarkation ramp allowed them to disembark one at a time. Spotlights in the front could be strategically used to blind enemies, and provide adequate lighting to the troopers on deployment. The cockpit was located in a raised chamber at the back of the ship.
Clone pilots flew the Aggressive ReConnaissance-170 starfighters also known as the ARC-170 starfighters, which would be later replaced by the TIE Fighters. In the Imperial era, there were a number of TIE fighters equipped for special missions such as interceptions, defence and bombing runs. The main model was the TIE Interceptor, which is known as the TIE/in. The First Order TIE Fighters were based on the Imperial TIE Interceptors, but had additional capabilities for defensive purposes. The models were known as TIE/fo Fighters.
Sources: Star Wars Databank, Star Wars Visual Dictionaries