I know I have a problem with obsessive-compulsive personality disorder, but so many people make the following mistake that I do feel the need to clarify. The only name at Disneyland that uses the word, "esplanade", is the East Esplanade where the hotel shuttles and the "Lion King" trams arrive and depart.
The piazza between the two parks is officially known as the Main Entry Plaza, although, since it occupies the central part of the Outer Lobby, I sometimes refer to the expanse as the central Lobby.
The Outer Lobby is everything on Disney property but outside the gates of The Magic Kingdom (parking areas; hotels; Downtown Disney; etc.), and the Inner Lobby is the area near the "Mickey Floral" parterre.