User blog comment:SuperSaiyanSimba/New Assassin's Creed Revelations Gamescom Trailer-Desmond has a beard!!!/@comment-4215643-20110817181837/@comment-1153722-20110817184435

What he is wearing is a sleeveless black shirt or blouse. Why would they show Subject 16? It's not confirmed we will be able to play as him, nor does he have anything to do with Altaïr for all we know.

The only reason why Desmond (and Ezio too, for that matter) looks slightly different is because the game uses a different engine than the other ones. A similar engine as the one that was used in L.A. Noire to realistically show facial expressions.