what exactly is the difference? or am i just a retard?
Since the difference in the game was already explained I'd figure I'd share a bit about the difference in real life.
The difference between the ASA cars and the Cup cars back then is kinda like the difference between the Hooters Pro-Cup (well whatever it's called now) cars & Cup (or well Nationwide) cars now.
Basically the ASA cars were a step below the NASCAR style Cup cars, but a step above a latemodel. The ASA National series cars were like that until the series demise in the early part of the decade, and the Pro-Cup cars have been like that for a while too.
The NASCAR Canadian Tire/CASCAR & NASCAR Mexican Corona style cars are pretty much like that too, they're a bit more then a Latemodel, but they're not really "enough" more to be on the same "shelf" as a Nationwide/East/West style car.