All-wheel drive (AWD) is a drivetrain system that allows all four wheels of a vehicle to receive power from the engine simultaneously. This system allows for better traction and stability during slippery conditions and can be found on almost any type of vehicle, from small cars to large trucks.
Four-wheel drive (4WD) is a drivetrain system that allows each wheel to be powered independently from the engine. This system is usually found on large off-road vehicles, such as SUVs and pickups, and is designed for rough terrain and towing heavy loads. 4WD is more powerful than AWD, but is not designed for everyday driving.