With such a ridiculously massive budget and multiple development studios involved, one would hope both versions of Call of Duty: Modern Warfare 3 turn out to be almost identical.
The major differences between multiplatform versions of a game always involve crucial elements; i.e., frame rate, visual fidelity, overall experience, etc. But Infinity Ward has once again stated that MW3 will offer PlayStation 3 and Xbox 360 owners the very same experience. As Robert Bowling told MS-Xbox World :
"No, the experience in terms of framerate, gameplay experience, features, visual fidelity, is going to be the same across Xbox 360 and PS3."
He didn't mention the fact that DLC is typically exclusive to Microsoft for some time before becoming available on the PlayStation Network. We believe that affects the "experience," but we appreciate what he's trying to say. We just hope the bugs and other little annoyances found in Black Ops won't be evident…'cuz those will be "the same" on both platforms, too.
Related Game(s): Call of Duty: Modern Warfare 3