My wife and I did a series of articles on taking toddlers and preschoolers to the 4 various parks. You got both, so here
Mouse Extra Mouse Extra
I hope it helps. Basically, its characters and shows for the kiddies. Personally, I think the DHS is the least appealing of the 4 for the real young kids. The parks have more rides for youngsters (MK and Epcot) or animals & better shows (DAK)