contusion vs black eye

contusion and black eye both are nouns.

Word	Noun	Adjective	Verb	Adverb
contusion	Yes	No	No	No
black eye	Yes	No	No	No

As nouns, black eye is a hyponym of contusion; that is, black eye is a word with a more specific, narrower meaning than contusion:

contusion: an injury that doesn't break the skin but results in some discoloration
black eye: a swollen bruise caused by a blow to the eye

Other hyponyms of contusion include ecchymosis, petechia, mouse, shiner.

contusion (noun)	black eye (noun)
the action of bruising	an unfortunate happening that hinders or impedes; something that is thwarting or frustrating
an injury that doesn't break the skin but results in some discoloration	a swollen bruise caused by a blow to the eye
	a bad reputation