Difference between AWD and 4WD?

Difference between AWD and 4WD?
Part-time 4WD is the original 4WD system and the most basic.

As with Full time 4WD there are several options available to the driver. In normal conditions the vehicle is driven in two-wheel drive, usually powering only the rear wheels. 4WD mode can be selected either by a separate mechanical lever or by an electronic switching system



AWD systems also lack the 'low range' feature which is common in most 4WDs.
The AWD system is less effective and more fragile than the 4WD system in a situation where high torque is required. Indeed, the viscous coupling units simply cannot satisfy high torque demands when the vehicle is offroad. AWD vehicles tend to be more 'car' like than obvious offroaders.