automatic weapon vs automatic firearm

automatic weapon and automatic firearm both are nouns.

Word	Noun	Adjective	Verb	Adverb
automatic weapon	Yes	No	No	No
automatic firearm	Yes	No	No	No

As nouns, automatic weapon and automatic firearm are synonyms defined as:

automatic weapon and automatic firearm: a firearm that reloads itself and keeps firing until the trigger is released

Other synonyms of automatic weapon include automatic gun.

automatic weapon (noun)	automatic firearm (noun)
a firearm that reloads itself and keeps firing until the trigger is released	a firearm that reloads itself and keeps firing until the trigger is released