The models (polygon wise) are the same in-game and in cutscenes in the first game. There were differences in lighting and shadows for cutscenes. Not sure what the differences are here...but I'd still say the models are exactly the same.
Edit: I think I might be able to prove that with these shots I've taken from the multiplayer. I don't believe the textures on skin is as high-res as in cutscenes, but still the models look the same IMO.
http://i34.photobucket.com/albums/d114/deepbrown/Uncharted2_AmongThieves.jpg
http://i34.photobucket.com/albums/d114/deepbrown/Uncharted2_AmongThieves_3.jpg
Would be quite impressive for Drake's multiplayer model to be the same 30k plus model as in the SP game - considering there can be up to 5 Drake's on screen at the same time.
Seen some upclose shots of the main characters on GAF and they certainly look way less than upclose angles in cutscenes/promo shots. Might also be the textures detail playing a role.