According to my passporter:
MK is 10 min
Epcot is 10 min
DHS is 15 min
AK is 15 min
DTD is 15 min by bus/ 20 min by boat
I'm asuming that does not take into to account that you might be picking up POR or waiting for the bus either.
Buses also go to the water parks. Use the DTD bus to go to TL and the AK bus to go to BB. There are no buses that go from resort to resort.