Microsoft has two separate platforms for web site integration, the first is the MapPoint Web Service. This has been around for a long time and might be considered to be more similar to MapQuest. This requires that you apply for developer credentials --
https://mappoint-css.partners.extran...nup/Eval2.aspx

The newer platform is Microsoft Virtual Earth (VE), this is what powers Live Local Search. This is open i.e.does not require authentication but still has restrictions on commercial use. VE is more like Google Maps.

hope this helps.
Eric