emptiness vs hollowness

emptiness and hollowness both are nouns.

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

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

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

emptiness (noun)	hollowness (noun)
the quality of being valueless or futile	the property of having a sunken area
an empty area or space	the quality of not being open or truthful; deceitful or hypocritical
the state of containing nothing	the state of being hollow: having an empty space within
having an empty stomach