R30, 31, 32, 33, 34, and V35
those are skyline but different year and model.
GT-R and GT-S
the GT-R is like top of the line for Skyline.
like top of the line Civic is Civic Type R.
yes, the performance is different. you can search on the net about it. or someone will come in and tell you more about it. i'm too lazy to search............................... ;D