User blog comment:Master Sima Yi/Assassinews 10-07-'13 — Assassin's Creed IV: Black Flag pirate gameplay naval exploration/@comment-5174994-20130711194930/@comment-4975789-20130711200320

I think they said the only differences would be graphics and small details (e.g. fauna physics, instead of animations), and that there would be no major differences. Or at least I hope they did.