The Main difference is in b/w sound signature,Build Qulity,Cable & Accessories.
Philips SHE 3590 is very basic IEM with a V-shaped sound signature that resembles a rock setting of any media player. With a mild base & treble boost that does not relent other spectrum of the music at moderate volume it almost sounds neutral. Most audiophile like this sound signature and hence the wildly popularity. With bear minimum accessories just 3 tip S,M,L it the very basic in what you can get for an upgrade to a stock earphone. other IEM which similar Sound signature is Sound Magic E10
Philips SHE 9700 has a sound signature that is Warm and smooth, enhanced bass level, laid-back treble & Emphasis on the mid-bass region. The IEM concentrates of mid bass more than on sub-bass. Sub-bass been as example of sony Xtra Bass line of IEM. (SONY MDR-XB30EX for example). The bass of Philips SHE 9700 is accurate & travels deep but also decays slow does making mid-bass seem more prominent in compare to other spectrum of the music. But been accurate & deep mid-bass is why its rated as highly on reviews sites. This along with the the tangle free & nice cord. Gold plated 3.5 mm audio jack. A case that has hard casing on the outside with enuf room to accumulate a small mp3 player like the clip & added tips makes it well worth the price asked about 1200 Rs. In addition to this both have a design which as a noise cancelling effect due to both can slide right into the ear canal and form a seal with the ear drum means that most external sound is blocked out. When you have them in and playing music at a reasonable volume it is difficult to hear much else. This makes them ideal for use on busy public transport & other noise environment.