請問all wheel drive 和 4 wheel drive 之分別

There are so many different 4WD systems on the market now that it is important to be precise and specific. It is important to call AWD when it is AWD and full time 4WD when it is full time 4WD. Just to say 4x4 is not sufficient any longer.

Full time 4WD, also called permanent 4WD, (not to be confused with: part time 4WD ) is a system that powers all four wheels at all times and can be used full time on all surfaces including pavement. The additional feature of a differential incorporated into the transfer case makes it possible to use 4WD all the time.
When " 4-low " is selected the wheels create substantially more torque than in " 4-high " - at the same time the vehicle moves at substantially slower speeds.
The low setting is an advantage for drivers who need to tow and maneuver a heavy trailer etc. and for drivers who at one point or another may want to negotiate difficult off-road terrain, when more torque and/or slower speed is needed.
Full time 4WD vehicles work very well on-road and are very capable off-road.

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. Full time symmetric AWD would be the best term to be used. Difference to full time 4WD 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.