How did submachine guns differ from rifles and pistols?

Submachine guns were developed to bridge the gap between the limitations of pistols and the cumbersome nature of rifles, specifically to provide soldiers with increased firepower for close-quarters combat.12

They differ from these other small arms in the following ways:

• Ammunition and Power: Unlike rifles, which fire high-power cartridges for long-range engagements, submachine guns are chambered for lower-energy, pistol-caliber ammunition. This results in a much shorter effective range, typically limited to about 200 yards (180 meters).12
• Firing Capability: While most pistols are semiautomatic, submachine guns are designed for automatic fire. They offer significantly higher rates of fire and greater accuracy than handguns, making them more effective for offensive assaults.12
• Design and Handling: Submachine guns are more portable and easier to handle than traditional infantry rifles, which were often too heavy and powerful for trench warfare or mobile combat. They typically feature shoulder stocks and box-type magazines, allowing for sustained automatic fire that a standard pistol cannot provide.12

Ultimately, the submachine gun served as a specialized tool for close-range effectiveness that neither the long-range rifle nor the low-power pistol could adequately address.2