achromia vs achromaticity

achromia and achromaticity both are nouns.

Word	Noun	Adjective	Verb	Adverb
achromia	Yes	No	No	No
achromaticity	Yes	No	No	No

As nouns, achromaticity is a hypernym of achromia; that is, achromaticity is a word with a broader meaning than achromia:

achromia: an absence of normal pigmentation especially in the skin (as in albinism) or in red blood cells
achromaticity: the visual property of being without chromatic color

Other hypernyms of achromia include achromatism, colorlessness, colourlessness.

achromia (noun)	achromaticity (noun)
an absence of normal pigmentation especially in the skin (as in albinism) or in red blood cells	the visual property of being without chromatic color