The previous poster is 100% on target when they said..."Read the signs"!
It is probably the biggest reason people complain about the bus service at WDW...they just haven't read the signs.
As stated, as you exit the parks and DTD, at night there are boards listing the bus stop #s and which resort (or location) corresponds to that stop...BUT they do change from time to time. For instance, the night we left
MVMCP at MK, the CMs were out there changing them as we walked by...so always look to be sure!
Each bus has a lighted sign on the front of the bus and on the side right next to the front door...like a city bus...read it! It tells you where the bus is headed. Some busses do have multiple stops...for example...
IF the bus says "Downtown Disney" it will stop at 2 locations in DTD; Marketplace and the West side (between Pleasure Island and Planet Hollywood), but the Marketplace stops service earlier than Westside...the bus driver typically announces this as you pull up to the DTD stops.
Some resort busses do share...i.e. the Yacht, Beach, Boardwalk, Swan, and Dolphin...may share a bus together or they may have only 2 resorts sharing one bus, or sometimes they have one for each, but usually Swan and Dolphin always share. The bus for Grand Floridian shares with either Wilderness Lodge, Polynesian, or Contemporary...these 4 share routes.
IF the bus shares a route...ALL the resorts will be listed on the bus sign on the bus...so READ IT!
Some bus stops share resorts...
for example at Epcot...bus stop #4 is the loading area for both SSR and OKW...there is only ONE line though, so you might find a group waiting for SSR then a few waiting for OKW and so on in the same line...keep your eyes peeled for the appropriate bus...again READ THE SIGN on the bus...so you get on the appropriate bus.
DTD does this alot...I think it's bus stop #3 that SSR, Contemporary, Polynesian, Wilderness Lodge share...in any case there is a sign telling you which bus stop # for which resort...but at DTD they are not dedicated to ONE resort, so again read the sign on the bus to be sure you are getting on the correct bus.
Getting from resort to resort...you will have to go from resort A, to one of the 4 parks, MK, MGM, Epcot, or AK, or to DTD and transfer to a different bus to get to resort B...it's not hard...just takes time.
The WDW bus transportation is not hard to figure out at all...just read the signs, and know when the bus service begins and ends at any location you will be at....the early ADRs at the parks...they do have bus service, but always check to be sure the time they start. If you have never used the system, it takes a day or so to get aclimated, but it's a great service! If you are familiar with any city bus system, then it should be a piece of cake. We live in rural America where bus systems are non-existent and love WDW bus transportation.