There are differences between the different console versions of Assassin's Creed IV: Blag Flag, but Ubisoft is also offering different content based on where you pre-order the game. Here's a comprehensive list of the differences between where you buy the game and for what system.
via N4G: pc news feed http://n4g.com/news/1370312/whats-the-best-way-to-buy-assassins-creed-iv-black-flag
via N4G: pc news feed http://n4g.com/news/1370312/whats-the-best-way-to-buy-assassins-creed-iv-black-flag