User blog comment:D. Cello/Assassin's Creed: Revelations (PC) - Official Assassin's Creed Wiki Review/@comment-5503561-20111205180836/@comment-99.112.68.66-20111213034929

Actually, they updated the graphics engine for ACR, so they had to redo the facial models for the game to look consistent (the developer said this in an interview, look it up)