mink vs American mink

mink and American mink both are nouns.

Word	Noun	Adjective	Verb	Adverb
mink	Yes	No	No	No
American mink	Yes	No	No	No

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

mink: slender-bodied semiaquatic mammal having partially webbed feet; valued for its fur
American mink: usually rich dark brown

Other hyponyms of mink include Mustela vison.

mink (noun)	American mink (noun)
slender-bodied semiaquatic mammal having partially webbed feet; valued for its fur	usually rich dark brown
fur coat made from the soft lustrous fur of minks
the expensive fur of a mink