Differences between Google Maps on google.com and ByTheOwner.com
Clients asked me lately why some streets weren’t showing on the maps we use for ByTheOwner when they do show on the maps.google.com website. Unfortunately, this ain’t due to a version bug, we can’t fix it. Here’s why.
The maps Google uses on his website are provided by Navteq. The maps we are allowed to use through the google maps api are provided by TeleAtlas. This is why the maps aren’t exactly the same everywhere. Navteq didn’t gave google the permission to share their maps through google’s api.

If you’d like to read more on the subject :
http://radar.oreilly.com/archives/2005/10/google_maps_and_their_data_pro_1.html
Frédérick Dubois, ByTheOwner.com
Web development and programming
