You do get the odd exception, like salopettes that are wider at the bottom to go over boots and the backs of bindings, or jackets that are a bit longer for a bit of padding when sitting down on the hill, but other than fashion and cosmetic stuff they both do exactly the same thing.
I ski but have bought what is essentially a boarding jacket this time - just 'cos I liked it!!
If anything, it seems a bit looser than a ski jacket, and I agree, maybe a bit longer - bonus is I have a funny rubbery waterproofy-type lining on the bottom of it, so when it's time for my chocolate break, I won't get a wet bum sitting on the snow!!
Probably deisgned specifically for all you boarders who seem to spend an enormous amount of time on your backsides!!