silence vs stillness

silence and stillness both are nouns.

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

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

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

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

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