The Yacht and Beach Club always share the same bus. Depending on the time of year, they may also share with the Swan and Dolphin (I've seen this before). I've never seen the hotels share with the Boardwalk too, but maybe it's happened in seasons of very low attendance.
All the resorts DO share the same boat service, which also connects to the Studios and Epcot; this may be what your friend is thinking about.
Incidentally, the Contemporary, Polynesian, and Grand Floridian also share bus routes sometimes, and Wilderness Lodge was even added on when I stayed at the Poly a few months ago!