Differences between open.maquest.com and nominatim.openstreetmap.org

Hi,

I thought the results would be the same, not depending on provider, but they aren't:
exemple with those queries:
http://open.mapquestapi.com/nominatim/v1/search.php?key=MY_KEY&addressde...
http://nominatim.openstreetmap.org/search?addressdetails=1&format=json&q...

I would love to get the (good) openstreetmap.org result in mapquest. I'm located in France but I don't think it matters.
At first I thought that there was a difference because of a delay in mapquest replication but it knows last for a month so it's not.

Any ideas?

Alexis