1. The PS3 has Bluray movies that have highest quality
2. The PS3 is best for photos, music, and videos on it's web browser
3. The 360 probably has best games as of now, but PS3 can catch up
4. PS3 has best graphics IMO.
Call of Duty 4 is awesome and is for both consoles. Don't know about Assasin's Creed, but it got amazing reviews.