Maybe because they don't run on the same hardware? Because both are designed to meet certain requirements which for the case of Crysis are so much higher allowing the developers more room to create better models, with more polys, with better textures, lighting, effects, etc?
Why is it that hard for so many people to understand that?
Apples and Oranges...
Compare MGS4 models to FFXIII models, that's all fine and well, both are PS3 games, etc.
And you like your increasing your post count posting several times in a row instead of quoting everyone in the same post ,don't you?