What is the difference between AWD and Automatic 4WD?

All wheel drive (AWD) is full time 4WD without 4WD Low. That's it - nothing more, nothing less.

Missing in the Consumer Guide description is automatic 4WD. Often falsely referred to as all wheel drive. Essentially a sophisticated 2WD system. Should be called part time AWD. Only one axle gets power most of the time. If that main driven axle (could be front or rear) loses traction a fully automatic system (hydraulic, mechanical or electronic) routes torque to the other axle as well. This means you have to completely lose traction in 2WD on your driven axle first and then the other axle will take over to keep the car moving. So, for a short moment you have AWD. Once the main driven axle regains traction and both axles rotate at the same speed again, the system reverts back to 2WD.

AWD means all four wheels are driven (usually all the time) such as Audi Quattro's. Automatic AWD means that the vehicle usually defaults to either front or rear wheel drive, but when the elcetronics sense wheel slippage, the other set of wheels kick in to assist. This is the set-up on vehicles like the Infiniti FX-35 AWD.

In an AWD car, all 4 wheels are driven, at all times. In an auto 4WD car, there are only 2 drive wheels active until the vehicle senses slip or traction loss from those 2 wheels...then it activates the remaining 2 wheels into drive.

all wheel drive (AWD) the computer in your car decides when to turn it on. 4 wheel drive you decide. Theres usually a switch or shifter you move.