boxfish vs cowfish

boxfish and cowfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
boxfish	Yes	No	No	No
cowfish	Yes	No	No	No

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

boxfish: any of numerous small tropical fishes having body and head encased in bony plates
cowfish: trunkfish having hornlike spines over the eyes

Other hyponyms of boxfish include Lactophrys quadricornis.

boxfish (noun)	cowfish (noun)
any of numerous small tropical fishes having body and head encased in bony plates	trunkfish having hornlike spines over the eyes