95-99 Eclipse/Talon

RS came with less options meaning no power windows, power locks, sunroof, cruise control, etc. unless someone ordered to have some or all put on from the factory. Also the RS has drum brakes in the rear. Comes with the 420a Non-Turbo Chrysler motor.

GS comes with all the options (pw, pl, sunroof, cruise control, sunroof), also the rear are disk brakes not drum like the RS. The GS also comes with the 420a Non-Turbo Chrysler motor.

GS-T comes with different options varies between years and so fourth but it comes with the 4g63t Mitsubishi Turbo Motor and its FWD (Front Wheel Drive)

GS-X same as the GS-T except for it AWD (All Wheel Drive)

And Dane doesn't know what he's talking about by saying GSX is the best choice for upgrading. Not getting a DSM is the best choice over any upgrade , if you decide to get one... hope you have deep pockets and patience... well atleast if you buy a turbo model.