All wheel drive (AWD) is almost the same thing as full time 4WD – it is a system that powers all four wheels of a vehicle at all times as well. It can be used full time on all surfaces, including pavement, like full time 4WD. The main difference is that a “4-low” setting is not available in AWD cars. Due to the lack of “low range”, AWD vehicles are much less capable in off-road settings than full time 4WD vehicles, but work perfectly well on-road.