* Fires one round each time the trigger is pulled.

* The shooter must release the trigger and pull it again for each shot.

* Typically holds a limited number of rounds in a magazine or clip.

Machine gun:

* Fires multiple rounds with one trigger pull.

* Can continue firing as long as the trigger is held down and there are rounds in the magazine.

* Typically holds a large number of rounds in a belt or drum magazine.

In addition to these basic differences, semi-automatic weapons and machine guns can differ in their design, caliber, and rate of fire.