I agree about launch game. They should still show clear differences and it will get worse as it gets later throughout the gen.Since I'm not ready to put my well known and much respected reputation on the line... I'll just post this here.
3rd Party games differences.
1. Games that have no competition in the genre (Madden 25) - minimal to no differences
2. Games that have other competition in the genre (Racing games ex. NFS Rivals) - there will be noticeable differences
3. Games that have marketing deals with Sony - noticeable differences
now the wild card situations are the 3rd Party games that have Microsoft exclusive deals like Titan. I'm guessing minimal to no differences (depends how the clouds align eh eh??)
this is more so long term...but at launch there should be alittle less differences across the board.
E3 should be awesome next year!