All-wheel-drive (AWD) and four-wheel-drive (4WD) sound synonymous, as if they were interchangeable terms. After all, vehicles usually have four wheels, so aren't four wheels all the wheels? Well, despite the terminology, these two systems operate differently and have a distinct physiology, even though they may perform the same basic task. Each system has advantages and disadvantages, each has a part-time and a full-time variation, and each functions in a different way. Further, it may be possible to spot said terminology through certain keywords when investigating potential vehicles to buy.

Read on to find out more about the distinctions, advantages, disadvantages, and differences of all-wheel-drive versus four-wheel-drive.

Related: Is This Next-Gen S650 Mustang Spied Testing An All-Wheel-Drive Platform?

The Inner Workings Of Both Types

Blue SUV parked in front of trees
via Green Car Reports

The way both mechanisms function are somewhat distinct from each other, although they both serve the same essential purpose.

In AWD, the driver doesn't need to consciously operate it, though various modes offer the driver various degrees of control regarding power. Multiple differentials deliver torque to all four wheels after properly distributing power for optimal traction and smoother performance.

With all-wheel-drive (AWD), there are two types of drivetrains: full-time AWD and part-time AWD. Full-time AWD will continuously drive all four wheels of the vehicle via both the front and rear axles. Meanwhile, the part-time AWD is automatic and continues to function while the vehicle is in two-wheel-drive mode, and more power may be required to attain additional traction control. In this scenario, extra power would be distributed among all four wheels, though once the scenario passes, the extra power is cut off. Also, the power is not distributed evenly- sensors give computers information to determine how much power each wheel should receive in a given scenario.

By contrast, four-wheel-drive (4WD) is a more traditional alternative, having been around since the birth of motorized vehicles. 4WD has evolved since those days, however, and is now widely used and delivers torque via transfer cases and couplings that allow vehicles to perform under maximum traction in various scenarios, sometimes using a series of front, rear and center differentials to deliver torque. Drivers also manually choose the range of torque delivered via a switch or lever. Low ranges offer maximum traction for off-road conditions while high ranges, which are the default setting, are better for inclement weather on paved streets. They share a function with AWD systems, as 4WD also sends torque to all four of a vehicle's wheels should more traction be necessary, though 4WD systems are more common for vehicles designed to handle more rugged terrain.

They have full-time and part-time versions as well. Full-time 4WD is incredibly similar to full-time AWD, though the driver manually controls power distribution to the axles. Part-time 4WD is more common and features two wheels, usually in the rear, doing all the driving for the vehicle. Should more control be needed, then the driver has to choose to engage the other two wheels.

Advantages And Drawbacks

truck struggling to get up hill
via Westerville Automotive

As to be expected, each system has its own advantages and disadvantages. 4WD is optimized for adversity in both on-road and off-road scenarios, with the main focus on ruggedness and maximum pulling power while traversing challenging terrain. This comes at a cost, however, as fuel economy pays the price and the initial cost of the vehicle is more expensive. 4WD also is usually the system used on bigger vehicles. It also locks the front and rear driveshafts together, which delivers equal amounts of torque to both driveshafts as they rotate at the same speed. However, should 4WD be regularly engaged on paved roads, the tires will wear out unevenly and the driveline will lock and make turning difficult.

With AWD, the driver doesn't have to consciously make decisions to engage the system, with the wheels and axles all constantly being driven and the system delivering power to various areas as needed. AWD also offers more flexibility, both in inclement weather and in on-roading versus off-roading. AWD also reduces fuel economy and increases cost just because of its presence and the features it offers.

Bottom line: the choice between AWD and 4WD should largely be based upon a driver's preference, the type of driving they will do, and what the terrain is like where they live. For example, 4WD is better for drivers living in remote areas or who enjoy off-roading, while AWD is better for drivers living in more crowded cities and stick to paved roads.

Related: 10 Best All-Wheel-Drive Cars Of 2019, Ranked

Imperative In Inclement Weather

Jeep barely making it up hill
via Wikipedia

Come rain, snow, sleet, or hail, knowing the difference could make driving an altogether safer experience. Although both AWD and 4WD are capable of losing traction, both also were designed with inclement weather in mind. Terrain changes frequently when inclement weather is involved. AWD can deliver four-wheel torque to all four wheels automatically faster than a driver can manually.

4WD, by contrast, is better for navigating heavier snow and icier roads. Drivers can get unstuck more easily when trapped in the snow. That said, four properly-fitting winter tires would be the most effective instrument against winter weather when combined with either AWD or 4WD.

Deciphering The Difference

Red SUV driving through muddy terrain
via CarsGuide

When looking to purchase a new car, sometimes there will be keywords in the advertisement or description that will reveal if the vehicle desired is AWD or 4WD. That said, auto manufacturers make this task exceedingly difficult.

After all, “all-wheel-drive” and “four-wheel-drive” are rarely explicitly used. Sometimes it's best to ask the salesman about the vehicle. Of note, however, is that Chevrolet brands its all-wheel-drive trucks as four-wheel drive, further confusing the issues. By contrast, Ford uses “four-wheel drive” to describe its all-wheel-drive SUVs. Audi's Quattro system also has multiple meanings depending on the vehicle.

The owner's manual should also distinguish between the two systems, though it may not use the terms explicitly either. When the manual discourages activating the system on dry pavement, that's a hint that the vehicle uses 4WD, and if this is not present, then the vehicle likely uses AWD.

Sources: edmunds.com, caranddriver.com, racv.com,

Next: Sure Footed: Toyota To Bring All-Wheel Drive To 2020 Avalon And Camry Sedans