distress call vs signalling

distress call and signalling both are nouns.

Word	Noun	Adjective	Verb	Adverb
distress call	Yes	No	No	No
signalling	Yes	No	No	No

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

distress call: an internationally recognized signal sent out by a ship or plane indicating that help is needed
signalling: any nonverbal action or gesture that encodes a message

Other hypernyms of distress call include sign, signal, signaling.

distress call (noun)	signalling (noun)
an internationally recognized signal sent out by a ship or plane indicating that help is needed	any nonverbal action or gesture that encodes a message