Does one of these portions of the article answer your question?
"Google’s Maps Engine, its enterprise-focused service for developers who need to be able to create their own maps based on custom data, launched about two years ago and has been available commercially since last year."
"You may be thinking that Google already has a Maps API, but as Dylan Lorimer, Google’s product manager for the Maps Engine API, told me, the regular Maps API mostly focuses on giving developers access to Google’s own mapping content. The Maps Engine API is meant to handle developers’ own data."
