boxfish vs plectognath fish

boxfish and plectognath fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
boxfish	Yes	No	No	No
plectognath fish	Yes	No	No	No

As nouns, plectognath fish is a hypernym of boxfish; that is, plectognath fish is a word with a broader meaning than boxfish:

boxfish: any of numerous small tropical fishes having body and head encased in bony plates
plectognath fish: tropical marine fishes having the teeth fused into a beak and thick skin covered with bony plates or spines

Other hypernyms of boxfish include plectognath.

boxfish (noun)	plectognath fish (noun)
any of numerous small tropical fishes having body and head encased in bony plates	tropical marine fishes having the teeth fused into a beak and thick skin covered with bony plates or spines