red drum vs drumfish

red drum and drumfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
red drum	Yes	No	No	No
drumfish	Yes	No	No	No

As nouns, drumfish is a hypernym of red drum; that is, drumfish is a word with a broader meaning than red drum:

red drum: large edible fish found off coast of United States from Massachusetts to Mexico
drumfish: small to medium-sized bottom-dwelling food and game fishes of shallow coastal and fresh waters that make a drumming noise

Other hypernyms of red drum include drum.

red drum (noun)	drumfish (noun)
large edible fish found off coast of United States from Massachusetts to Mexico	small to medium-sized bottom-dwelling food and game fishes of shallow coastal and fresh waters that make a drumming noise