No there really is not that big of a differance. When I was at EB for our tournament a couple weeks ago they had an Xbox set up right next to a PS2 both running MK:DA.
I only played a few rounds (on Xbox), but I wasn't impressed. The characters looked exactly the same, I think the only visual difference was some better anti-aliasing on parts of the backgrounds.
The gameplay on the other hand was a lot different. For instance the few rounds I played I used Shang, and for the life of me I could not squeeze the L button hard enough to pull of his basic 1,1,2,cs combo, yet switching styles while just standing there was a breeze!