Anti-tank guns are typically high-velocity guns designed to fire anti-tank shells.
They are usually designed to be easily transported and concealed to maximize responsiveness and surprise.
Self-propelled anti-tank guns are anti-tank guns mounted on vehicles.
Sometimes lightly armored, and often fitted into a turret, they are nonetheless not tanks or assault guns and simply enhance the mobility of anti-tank guns.
They are also capable of providing direct fire support.