Near as I can tell, "navigate to" gives it a lot more leeway to go psychotic and take whatever scenic route it wants to get there. "Drive to" makes them stop at a red signal and wait for it to turn green instead of trying to find an alternate route (longer and convoluted) so it don't have to wait a few minutes for the track to clear. This;
Ok, that makes sense. Drive to= go from A to B direct, no foolishness. Navigate to= be creative. This must be why some of my AI trains just make no sense whatsoever. Gonna go change that right now. Thanks