Assault Gun Vs. Tank Destroyer: What's The Difference Between These Armored Vehicles?

It's not uncommon for civilians to see an armored fighting vehicle (AFV) with caterpillar tread and a large cannon and call it a tank. Those are the basic features that make up a main battle tank, after all. However, armored vehicles are much more nuanced than most people think, so just because it looks like a tank and it moves like a tank doesn't mean it is one. Tank destroyers and assault guns are two other armored vehicles with a cannon and tread, but aren't actually tanks. These two vehicles have more in common with one another than they do with main battle tanks, in fact.

Tanks are designed to tackle a variety of threats in a war zone, whereas tank destroyers and assault guns have more focused roles. Unlike the light tanks that existed before World War II, destroyers and assault guns proved their worth so well they're still developed today. Read ahead to see how these two AFVs differ from each other.

Tank destroyers came about during World War II as a method for combating main battle tanks. Some of the best tank destroyers of WWII looked similar to tanks but favored firepower, long range, and mobility over other features commonly seen on tanks, such as armor or even turrets. Less armor meant destroyers were faster than their prey, while the longer guns allowed them to attack tanks from a distance. Destroyer armor was typically thicker in the front than on its sides or rear. 

One of the tougher tank destroyers was made by Ford during World War II. The M10A1 was good at what it did, seeing action in Normandy and the Battle of the Bulge, but had a short production life from 1941 to 1943, as its armor and top speed fell below the standard of other tank destroyers of the time. 

Germany, America, and the Soviet Union were the primary armies to use tank destroyers during WWII. While Germany and the Soviets built their tank destroyer turrets with a limited traverse, America built its destroyers with fully traversable turrets, thus they're closer in appearance to tanks. Destroyers like the M10 Wolverine were even built on an M4 Sherman tank chassis, further adding to the similarities in appearance.

Assault gun is a confusing name because it sounds similar to assault rifle, but the assault gun isn't something that can be slung across a soldier's chest. It's a mobile cannon often built on a tank chassis. These AFVs are a type of self-propelled gun (SPG) that focused on direct-fire tasks in World War II. However, unlike tanks, early versions had a fixed, armored superstructure rather than a turret. They're not as versatile as tanks and serve a different purpose on the battlefield to tank destroyers. Assault guns are designed to provide support for infantry units, targeting opposing infantry, lightly armored vehicles, and enemy fortifications.

The German StuG III Assault Gun in World War II was a threatening piece of artillery that the allied forces had to watch out for — it destroyed a significant number of AFVs during the war. However, the German forces started using their assault guns as tank destroyers when their inventory ran low, fitting 75 mm anti-tank guns to the StuG IIIs, along with the 75mm Howitzer already featured. 

Assault guns aren't a thing of the past. The U.S. Army's next combat vehicle, the M10 Booker, is classified as an assault gun. You can count on the United States to make one that closely resembles main battle tanks.