Assisted GPS IS true GPS, it just uses cell towers to get an initial lock on you so that it takes less time for the GPS satellites to get a lock on you since they'll have a rough idea of where you are. In anything, AGPS has more functionality than the GPS units you have in cars.
Not quite. AGPS is NOT gps. True, it can reduce the amount of time it takes for a true GPS receiver to get a lock on the satellites (the satellites don't lock on you) but you can't get the precision you need for navigation applications with AGPS alone. I'm not an RF engineer so if I'm wrong, I'd love to hear it.