stillness vs silence

stillness and silence both are nouns.

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

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

Other hypernyms of stillness include quiet.

stillness (noun)	silence (noun)
(poetic) tranquil silence	the absence of sound
calmness without winds	a refusal to speak when expected
a state of no motion or movement	the trait of keeping things secret
	the state of being silent (as when no one is speaking)

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