quietness vs silence

quietness and silence both are nouns.

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

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

Other hypernyms of quietness include quiet.

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

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