leatherjacket vs leatherfish

leatherjacket and leatherfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
leatherjacket	Yes	No	No	No
leatherfish	Yes	No	No	No

As nouns, leatherjacket and leatherfish are synonyms defined as:

leatherjacket and leatherfish: any of several brightly colored tropical filefishes

leatherjacket (noun)	leatherfish (noun)
any of several brightly colored tropical filefishes	any of several brightly colored tropical filefishes
any of several New World tropical fishes having tiny embedded scales
tough-skinned larva of certain crane flies