alarm vs signalling

alarm and signalling both are nouns.

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

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

Other hypernyms of alarm include sign, signal, signaling.

alarm (noun)	signalling (noun)
a device that signals the occurrence of some undesirable event	any nonverbal action or gesture that encodes a message
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

alarm (verb)	signalling (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