emptiness vs vacuity

emptiness and vacuity both are nouns.

Word	Noun	Adjective	Verb	Adverb
emptiness	Yes	No	No	No
vacuity	Yes	No	No	No

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

Other hyponyms of emptiness include blankness, hollowness, vacancy, vacuum.

emptiness (noun)	vacuity (noun)
the quality of being valueless or futile	total lack of meaning or ideas
an empty area or space	a region that is devoid of matter
the state of containing nothing	the absence of matter
having an empty stomach