I think this was a rather weak screenshot comparison, in reality overall the differences are much greater and to really appreciate this you will have to see the game running side by side.
http://www.gametrailers.com/gamepage.php?id=3450 (Check out the review)
However I don't think the developers significantly overhauled the game engine to get the most out of the PS3, I still think this is an excellent port overall. Probably at this point the PS3's and XBox 360's best overall game if you don't mind playing it by yourself.
Has been a worthy purchase for me!