silence vs quietness

silence and quietness both are nouns.

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

As nouns, quietness is a hyponym of silence; that is, quietness is a word with a more specific, narrower meaning than silence:

Other hyponyms of silence include hush, still, stillness, speechlessness, soundlessness.

silence (noun)	quietness (noun)
the absence of sound	the property of making no sound
a refusal to speak when expected	a state of peace and quiet
the trait of keeping things secret
the state of being silent (as when no one is speaking)

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