4WD AWD 4X4, Whats the difference?

[j1rm]

Why name it differently if they do the same thing, is 4x4 the same as the rest?

[PapaSmurf2k3]

4wd and 4x4 typically have open differentials on the front and rear of the car, and a transfer case in the middle so that it will split power between the front and the back, but with the open differentials you get 1wd on front and back, so really 4x4 and 4wd are usually 1 wheel driving in the front, and 1 in the back.

AWD usually has electonic differentials that put power to all 4 wheels, and some systems sense slipping wheels, and transfer power away from them to gripping wheels.

[SteveTheTech]

The way the modern AWD systems work is via an electronic coupler that by using varying current supply adjust the amount of power sent to either axle. The slip ratio is adjusted when the ABS system detects wheel speed variance of ~3mph. In a typical Infiniti (RWD normally) under most driving conditions almost if not all the torque is applied to the rear wheels. Under heavy acceleration or wheel slip, or decel/G sensor input the ATTESSA systems will divert the needed power to the front wheels to regain traction. This operation is used in conjunction with a momentary cut in throttle output and fuel injection pulse. In Nissan (FWD normally) torque is applied to the front wheels until the above mentioned parameters are met to warrant a torque split. Torque split can be varied for 0-80% in most vehicles with advanced traction control.

4WD usually involves a direct torque split with lockable hubs(either electromagnetic or old school vacuum, or archaic manual). AWD cars (Nissan/Infiniti) do not have locking hubs or a 4H/4L option like many trucks and SUVs have.