symbol vs signalling

symbol and signalling both are nouns.

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

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

symbol: an arbitrary sign (written or printed) that has acquired a conventional significance
signalling: any nonverbal action or gesture that encodes a message

Other hypernyms of symbol include sign, signal, signaling.

symbol (noun)	signalling (noun)
something visible that by association or convention represents something else that is invisible	any nonverbal action or gesture that encodes a message
an arbitrary sign (written or printed) that has acquired a conventional significance