Brevoortia tyrannis vs menhaden

Brevoortia tyrannis and menhaden both are nouns.

Word	Noun	Adjective	Verb	Adverb
Brevoortia tyrannis	Yes	No	No	No
menhaden	Yes	No	No	No

As nouns, Brevoortia tyrannis and menhaden are synonyms defined as:

Brevoortia tyrannis and menhaden: shad-like North American marine fishes used for fish meal and oil and fertilizer

Brevoortia tyrannis (noun)	menhaden (noun)
shad-like North American marine fishes used for fish meal and oil and fertilizer	shad-like North American marine fishes used for fish meal and oil and fertilizer