monochromia vs colour blindness

monochromia and colour blindness both are nouns.

Word	Noun	Adjective	Verb	Adverb
monochromia	Yes	No	No	No
colour blindness	Yes	No	No	No

As nouns, colour blindness is a hypernym of monochromia; that is, colour blindness is a word with a broader meaning than monochromia:

monochromia: complete color blindness; colors can be differentiated only on the basis of brightness
colour blindness: genetic inability to distinguish differences in hue

Other hypernyms of monochromia include color blindness, color vision deficiency, colour vision deficiency.

monochromia (noun)	colour blindness (noun)
complete color blindness; colors can be differentiated only on the basis of brightness	genetic inability to distinguish differences in hue