mum vs silence

mum and silence both are nouns.

Word	Noun	Adjective	Verb	Adverb
mum	Yes	Yes	No	No
silence	Yes	No	Yes	No

As nouns, silence is a hypernym of mum; that is, silence is a word with a broader meaning than mum:

Other hypernyms of mum include secrecy, secretiveness.

mum (noun)	silence (noun)
secrecy	the absence of sound
informal terms for a mother	a refusal to speak when expected
of China	the trait of keeping things secret
	the state of being silent (as when no one is speaking)

mum (adjective)	silence (adjective)
failing to speak or communicate etc when expected to

mum (verb)	silence (verb)
	cause to be quiet or not talk
	keep from expression, for example by threats or pressure