There are noticeable differences between both models. Just go research the subject a little bit with the links I gave you. They have similar torque figures, but the HP is more on the GTS. The GT is a 5 spd., the GTS a 6 spd. (manuals). Both offer Auto.
I don't know what you want, I can't tell you what to get!
Look at the "build your own" option on the Toyota site.
http://www.toyota.com
Or check out the specs between the two. Compare them side by side.
later,
chris