largemouth bass vs black bass

largemouth bass and black bass both are nouns.

Word	Noun	Adjective	Verb	Adverb
largemouth bass	Yes	No	No	No
black bass	Yes	No	No	No

As nouns, black bass is a hypernym of largemouth bass; that is, black bass is a word with a broader meaning than largemouth bass:

largemouth bass: a large black bass; the angle of the jaw falls behind the eye
black bass: widely distributed and highly prized American freshwater game fishes (sunfish family)

largemouth bass (noun)	black bass (noun)
a large black bass; the angle of the jaw falls behind the eye	widely distributed and highly prized American freshwater game fishes (sunfish family)
flesh of largemouth bass	bluish black-striped sea bass of the Atlantic coast of the United States