there isnt much difference between them on paper, its when you drive them you notice theyre much nicer to drive, i think the basic differences are : different turbo, dual air bag, different front seats, different tune (engine, they have r34 coilpacks) and a few other bits and pieces its too late at night to remember lol.NOTE: like most things, with a skyline you get what you pay for so dont look for the cheapes, look for the best one you can afford
p.s thanks