There are 3 seaparate monorail lines. Two follow the same path, going to the magic kingdom, although go in opposite directions. One of them is an express, stops at the magic kingdom and transportation and ticket center(TTC). Although it goes past the resorts stops, it does not stop. The resort line goes in the opposite direction around the same loop, but does stop at all three resorts as well as the transportation center and the magic kingdom. If you want to get to epcot, you need to take the monorail to the TTC and change there to the epcot monorail. That one runs on its own loop, just between epcot and the TTC.
If you are staying at the contemporary or grand floridian and want to go to epcot, you would take the monorail to the TTC and change to the epcot monorail line. if you are staying at the Polynesian, you can walk to the TTC and get the epcot monorail.