dichromasy vs colour blindness

dichromasy and colour blindness both are nouns.

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

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

dichromasy: a deficiency of color vision in which the person can match any given hue by mixing only two other wavelengths of light (as opposed to the three wavelengths needed by people with normal color vision)
colour blindness: genetic inability to distinguish differences in hue

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

dichromasy (noun)	colour blindness (noun)
a deficiency of color vision in which the person can match any given hue by mixing only two other wavelengths of light (as opposed to the three wavelengths needed by people with normal color vision)	genetic inability to distinguish differences in hue