These aren’t just all-wheel drive designations. There is a significant difference between them.
What does 4WD mean?
Often referred to as 4WD or 4×4, this all-wheel drive system does exactly what the name suggests: it sends engine power to all four wheels. A 4WD system usually also includes a transfer box with downshifts that are activated by a separate lever or by buttons (rotary switches). This increases the torque of the wheels and allows you to overcome difficult terrain at low speed.
Such an all-wheel drive system can constantly transmit torque to all four wheels, and the driver can disconnect and connect one of the axles.
Some modern off-road vehicles can decide for themselves when one of the axles should be engaged or disengaged, similar to an AWD all-wheel drive system.
What does AWD stand for?
AWD systems, such as 4WD systems, can also send engine power to all wheels. Likewise, the all-wheel drive system can engage or disengage one of the axles. But AWD systems do not always allow the driver to intervene in the connection-disconnection process.
AWD vehicles turn only one axle most of the time, turning the other two wheels as needed when the car “feels” slip on one of the drive wheels. In this case, a different amount of torque can be transmitted to the connected axis (for example, from 10% to 50%).
Unlike a 4WD system, AWD systems don’t have a transfer case.
Engineering or marketing
I must say that AWD systems are gradually replacing 4WD systems equipped with real SUVs. We can say this: the first system is good on asphalt and speed, and the second is good on the ground with measured movement. That’s why there are crossovers (with AWD system) and SUVs (with 4 WD system).
differentials
Another thing that distinguishes an AWD system from a 4WD system is the type of differentials used. In the AWD system, designed for active driving, the differentials are found not only on the front and rear axles, but also between the axles (responsible for the percentage of torque transfer to the connected axle). In 4WD systems, a center differential is rare, especially if the car is primarily intended for off-road driving.
Transfer case
Considered by many to be one of the main distinguishing features of a 4WD system, the transfer case is an additional set of reduction gears that allows the wheels to spin more slowly at high engine speeds. This greatly improves the vehicle’s off-road handling. AWD systems don’t have a transfer box, so they don’t perform as well off-road.
What’s better
It all depends on where your car is most often driven. If you are going off road, you definitely need a 4WD system with a transfer box. However, if on asphalt and at high speeds, when safe traction is important, especially in bad weather and in winter, you won’t find a better AWD system.
