I have both Copilot Live USA and NDrive installed. I prefer Copilot because of the available traffic service; NDrive's traffic service in only available in Portugal.
NDrive uses TeleAtlas maps. The current US maps are from March 2010, making them 9 months old. I have no idea if/when an update will be available. Despite this, NDrive's maps are much more up to date that Copilot's, which I received an update for about two weeks ago.
I don't really use NDrive (I was using a dedicated TomTom prior to Copilot), but I do have both Copilot and NDrive, and I can check things out if you have a specific question.
** somewhat off topic **
While no traffic service is perfect, I compared Copilot's traffic information to my TomTom Go 740 Live traffic for almost two months side-by-side while driving, and found Copilot's traffic information to be closer to reality. Because of TomTom's IQ Route technology, traffic congestions that's considered normal for that time of day and day of week isn't shown, as it's built in to the estimated travel speed for the roadway. This makes it difficult to compare traffic info, but despite this, TomTom still had a lot of false positives (indicating traffic where there was none) in areas where Copilot did not.