fire alarm vs alarm

fire alarm and alarm both are nouns.

Word	Noun	Adjective	Verb	Adverb
fire alarm	Yes	No	No	No
alarm	Yes	No	Yes	No

As nouns, alarm is a hypernym of fire alarm; that is, alarm is a word with a broader meaning than fire alarm:

Other hypernyms of fire alarm include alarm system, warning device.

As nouns, alarm is a hypernym of fire alarm; that is, alarm is a word with a broader meaning than fire alarm:

Other hypernyms of fire alarm include alarum, alert, warning signal.

fire alarm (noun)	alarm (noun)
an alarm that is tripped off by fire or smoke	a device that signals the occurrence of some undesirable event
a shout or bell to warn that fire has broken out	a clock that wakes a sleeper at some preset time
	an automatic signal (usually a sound) warning of danger
	fear resulting from the awareness of danger

fire alarm (verb)	alarm (verb)
	warn or arouse to a sense of danger or call to a state of preparedness
	fill with apprehension or alarm; cause to be unpleasantly surprised