AA Wise, mostly they are similar, just achieved in different ways..
Some people seem to be glad for the drop in res + soft filter on the PS3, giving a more 'natural' scene, however, for me, it just adds a sheen of softness that gives my eyes a hard time if you sit too close..
The 'style' R* chose is a bit marmite, but I love it, I know it's done to help graphically, and I don't care..
My advice, sit further back from the screen, like watching Freeview/Sky on a HDTV, stick your nose to the glass and it looks hideous, step back 6ft and it starts looking like it should..