Microsoft’s answer to Google Maps is Virtual Earth. Obviously Microsoft uses other data for their maps. Alltogether Google Maps appear to be nicer, faster, a little more precise and with better aerial imagery. Microsoft sometimes uses BW images – maybe from the infrared spectrum. Microsofts product also sometimes fails to load all tiles of the current view. On the positive side Virtual Earth offers more detailed information per zoom level that are hidden in Google Maps it features a very cool local search (with auto update). There is also an API similar to the Google Maps API. This allows to create a comparison site like this.
A little bit disturbing is how old the satellite images at Microsofts Virtual Earth are. If you zoom in the comparison example you can see that Apple Inc. wasn’t even build.