There is an awesome thread that Jeff started and compiled great comparison info on the two parks. My favorite part is the distances and how he was able to explain how crazy compact DLR is vs. WDW with just the below snippet. But goes into more detail on the distances (and other great things) over in Disneyland for WDW Veterans
And yes, walking between the parks really is like walking between the area formerly known as Future World and World Showcase, but with that whole area being a wide open plaza instead of the pathways and lagoons that exist between the two areas in Epcot.