I'm not sure anymore.  If you have the original window sticker that the dealer generally puts in your owners' manual, it will tell you what option packages it has on it.  The GT2 was the higher end package.

GT1 is the base model (cloth seats am/fm w/ cd, usually no power seat, etc).  GT2 will have sunroof, pwr seats, disc changer, and other accessories like that.  As far as engine or any other specs they are the same.