siren vs alarm

siren and alarm both are nouns.

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

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

siren: an acoustic device producing a loud often wailing sound as a signal or warning
alarm: a device that signals the occurrence of some undesirable event

Other hypernyms of siren include acoustic device, alarm system, warning device.

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

Other hypernyms of siren include alarum, alert, warning signal.

siren (noun)	alarm (noun)
eellike aquatic North American salamander with small forelimbs and no hind limbs; have permanent external gills	a device that signals the occurrence of some undesirable event
an acoustic device producing a loud often wailing sound as a signal or warning	a clock that wakes a sleeper at some preset time
a warning signal that is a loud wailing sound	an automatic signal (usually a sound) warning of danger
a woman who is considered to be dangerously seductive	fear resulting from the awareness of danger

siren (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