the Clio 172 and 182 (aka full fat) have all the toys, air con, half leather, xenon lights, late 172s and all (i think) 182 have cruise control and a couple other toys i cant think of.
the 172 cup has no aircon (unless its a silver one) no xenon lights, no half leather, no cruise, no abs, no traction control but comes with cool wheels and the blue ones are a really nice colour.
the 182 cup isnt quite as hardcore as the 172 cup as it has abs and traction control etc.
the thing with Renault engines is they dont all put out the same power so you cant really say a 172 cup is faster than a 182 as they all vary. to be honest i wouldnt want to lose all the toys and go for a cup just because it could be slightly faster round a track
someone will be able to go into more detail on this as i dont know the full story with them.
EDIT: also the 182 comes with whats known as the cup packs, think their was 2, 1. cup spoiler pack and 2. cup suspension pack.
the cup spoiler pack gives you a splitter and better looking spoiler and the cup suspension gives you the dark (anthracite) wheels and its got stiffer springs which also lower it slightly but you can hardly notice the ride hight difference