whalesucker vs suckerfish

whalesucker and suckerfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
whalesucker	Yes	No	No	No
suckerfish	Yes	No	No	No

As nouns, suckerfish is a hypernym of whalesucker; that is, suckerfish is a word with a broader meaning than whalesucker:

whalesucker: large blue Pacific remora that attaches to whales and dolphins
suckerfish: marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects

Other hypernyms of whalesucker include remora, sucking fish.

whalesucker (noun)	suckerfish (noun)
large blue Pacific remora that attaches to whales and dolphins	marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects