Ubuntu is an out-of-the-box distro. You don't have to install anything in it except the proprietary AMD Catalyst driver.
With Arch...you start with nothing but command line and have to download packages and configure them step by step. Installation takes time depending upon your download speed - as you are downloading packages and configuring them on the fly. End result is - you only have things which you need. Nothing more and nothing less. Not a distribution for beginners in any case but it is the fastest Operating System around because of its "no bloat" philosophy.
The user experience depends on which Desktop Enviroment you choose to install. I am using GNOME 3 + Shell in the above screenshots. Some people prefer KDE 4.7. Ubuntu uses GNOME 3 + Unity.