Sorry, buses don't (generally) go from resort to resort. The best way I can think of to get to Poly from AoA is to bus to MK, then get on the boat to Poly. You can also ride the resort monorail to Poly, but I think in this case the boat would be quicker.
Returning to AoA, just reverse the process, except in this case the monorail from Poly to MK would probably be faster than the boat.