Also much better music on SM in Disneyland!
I think one day is plenty for MK if you are very familiar with DL rides and are happy doing everything new just once. I'd probably skip Small World at WDW -- it's very similar in most respects but missing the Disney movie character appearances that Disneyland has. Pirates of the Caribbean is also not as good. Could probably also skip Buzz Lightyear, because it's very similar and also lame IMO.
I suggest getting FPs for Space Mountain, Mine Train, and Jungle Cruise. Get Thunder Mountain, Splash Mountain and Haunted Mansion done at rope drop.