We've bought the HP package for a week in December. It includes Early Park Admission. From what I remember of the small print, that was admission 1 hour early, for the Wizarding World of Harry Potter, Dueling Dragons, Flight of the Hippogriff and the Cat in the Hat (reserving the right to change without notice, of course).
I don't know about non-HP packages, but I'm sure someone else here does!