largemouth vs black bass

largemouth and black bass both are nouns.

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

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

largemouth: 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 (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)
	bluish black-striped sea bass of the Atlantic coast of the United States