Through (perhaps a little bit too much, lol) comparison of both versions:
http://www.eurogamer.net/articles/digit ... ff-article
Both systems' internal architectures differ so much, developers should as well disregard middleware entirely and work to each one's strong points in order to extract really good performance out of them.
Briefly: the Xbox 360 version runs below 720p while PS3 runs at, err, "718p". The 360's 10 megabytes of embedded RAM allow for a much higher bandwidth that can be used for alpha effects, one of which was the extreme blood gushes and blood stains, and more on-screen polygons, most of the time this means more enemies thrown at you at once, busier-looking cutscenes and their severed limbs lying around the place. On real-time generated cutscenes, it looks like they just run at the highest framerate possible on 360 and are v-locked at 30 fps on PS3 (this assures that there'll be no screen tearing in the latter).
Where the 360's graphics processing power is focused on vertex shading and high polygon count, PS3's Sigma 2 focuses on pixel shaders and the additional level of detail on the stages.
Maybe Team Ninja's remaining members could have used the Cell processor's SPUs to keep the lost geometry, as was the case with Naughty Dog's gorgeous looking
Uncharted 2, but maybe that would have represented way too much work for their deadline.