automatic firearm vs autoloader

automatic firearm and autoloader both are nouns.

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

As nouns, autoloader is a hypernym of automatic firearm; that is, autoloader is a word with a broader meaning than automatic firearm:

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

Other hypernyms of automatic firearm include self-loader.

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