After the Disney company realized they couldn't (or didn't want to try to) build Walt's dream for EPCOT, they realized that WDW as a whole was realizing some of the Walt's original plans for EPCOT (take its cue from the new ideas and new technologies that are now emerging, always be introducing and testing and demonstrating new materials and systems, EPCOT (read WDW) will always be a showcase to the world for the ingenuity and imagination of American free enterprise, etc). The Disney company dubbed ALL of WDW as EPCOT and then created EPCOT Center the theme park in the middle of it. Personally, I think that is a little bit (or a lot) of company spin, but I think that is what Yoho is talking about.
Danny Kaye explains it at 3.28 in the following video from the Disney special when EPCOT Center openned.
http://youtube.com/watch?v=EZBqbeRGuzw