Big differences
GTT is the GTR's little brother... different engine, twin turbo = GTR, single turbo for GTT, less power than GTR, GTR is 4wd, GTT is rwd, interior is all different - bucket seats for GTR, bigger wheels for GTR... flaired guards on GTR, different body kit,
way to much different to mention...
GTT = Gtst if you know what they are