silence vs quieten

silence is a noun but quieten is not a noun.

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

As verbs, silence and quieten are synonyms defined as:

Other synonyms of silence include hush, hush up, shut up, still.

silence (noun)	quieten (noun)
the absence of sound
a refusal to speak when expected
the trait of keeping things secret
the state of being silent (as when no one is speaking)

silence (verb)	quieten (verb)
cause to be quiet or not talk	cause to be quiet or not talk
keep from expression, for example by threats or pressure	make calm or still
	become quiet or quieter