Disneyworld is set up like four different theme parks (each with their own admission fee)
Magic Kingdom is similar to Disneyland
Epcot is more of a global-wonders of mankind type thing
Animal Kingdom is much like it sounds
Disney-MGM studios is the one that has the Muppets.
It's a movie based theme park with Star Tours and Backlot tours and the like.
They've recently opened a second park across from Disneyland called California Adventure, and I think they have a Muppet 3D there too, but I could be wrong.