Self-Propelled Artillery Vs. Tanks: What's The Difference?

To a layperson looking at a tank beside self-propelled artillery, they probably look similar enough that they don't see much of a difference. Ask an artillery servicemember, and they'll tell you their vehicles are tanks, but a tanker might not agree. While they do look similar, they are different in many ways that make them distinct from one another. That said, they have many features in common, which could be a source of confusion for many people. They are both armored vehicles with massive weapon systems used as their primary means of engaging targets.

They also have similar defenses, countermeasures, crew sizes, and much more. Still, despite these commonalities, a tank isn't the same as self-propelled artillery, and there's a reason for this. Tanks are used primarily for direct engagement with an enemy via large shells, and self-propelled artillery is used to provide indirect fire support against enemy locations by firing shells, rockets, and other munitions. These distinctions are important because you cannot use a tank as self-propelled artillery and vice-versa — they truly are different pieces of equipment.

Throughout the 20th century and in modern combat operations spread around the world, militaries employed both tanks and self-propelled artillery. Napoleon proved the efficiency of artillery in combat, and that's not something commanders have forgotten. Tanks have proven their effectiveness in combat operations for more than a century, so they, too, have their place on the battlefield. Here are the differences between the two, as well as their primary functions in combat and general overall capabilities.

Self-propelled artillery provides indirect fire support with a weapon that is often a much larger caliber than a tank. The "self-propelled" designation centers around the fact that these massive guns are able to move independently, typically on tracks (like a tank). It's an important distinction because, for most of history, artillery had to be towed or carried by other vehicles to a specific position for use. Self-propelled artillery is able to move on its own, establish itself in a location, and begin a fire mission without assistance.

The U.S. uses the M109A6 "Paladin" Howitzer as its primary self-propelled artillery. A howitzer is capable of firing at low-angle fire as a field gun and at a high angle as a mortar, so it has a variety of uses. Still, it is an artillery piece capable of delivering significant firepower up to 11.24 miles away from its position. It boasts a 155mm 39 caliber M185 primary weapon system with 36 rounds stored onboard, though some variants have up to 52 caliber guns. Like many tanks, it also has a .50 caliber machine gun and requires a crew of four personnel.

Because the Paladin is a howitzer, it can engage in direct combat if needed. This makes it more of a multirole weapon system than a traditional tank or self-propelled artillery, but most don't have this capability. For example, a Multiple-Launch Rocket System (MLRS) like the HIMARS is limited to indirect fire. The U.S. primarily uses the M270 MLRS and M142 HIMARS for this purpose, and like the Paladin, they're armored, self-propelled, tracked and wheeled vehicles.

In terms of military technology, tanks are relatively new, having first been used in World War I. Primarily, tanks are designed to fight other tanks, so they're more heavily armored than most self-propelled artillery. They directly engage with tanks, other vehicles, equipment, and dismounted enemy combatants. To this end, they're often equipped with machine guns and other arms designed for this type of engagement. The U.S. military uses one of the most fearsome military tanks ever built, the M1A2 Abrams Main Battle Tank.

The Abrams, and tanks like it, feature a variety of armor types built from composite material. It also features explosive reactive armor and other methods of safeguarding the vehicle and its crew. During Operation Desert Storm, Abrams tanks took out Iraqi T-72s with such ease it wasn't much of a challenge, and U.S. tanks could take fire and continue operating. Most impressive is its main gun, a 120mm M256 smoothbore capable of firing various ammunition types up to 2.48 miles from its position.

While devastating to other tanks, that's a considerably shorter range than a standard self-propelled artillery piece. Therein lies the main difference because, while both weapon systems are deadly and capable of bringing great destruction upon an enemy, they each have their own unique capabilities. These come with advantages and disadvantages, so while a howitzer can destroy a tank from a great distance, within the tank's firing range, the artillery is disadvantaged. Similarly, a tank can't strike a self-propelled artillery piece outside its firing range.