What is the difference between AWD and 4WD?

All-wheel drive automatically sends power to all four wheels as needed and is designed for everyday traction on wet, snowy or gravel roads. Four-wheel drive is typically a more rugged system, often with a low-range gear, meant for off-road use, deep snow, steep trails and heavy towing on loose surfaces. Most drivers on paved roads are well served by AWD, while 4WD suits off-roading and rough work.