whitefish vs seafood

whitefish and seafood both are nouns.

Word	Noun	Adjective	Verb	Adverb
whitefish	Yes	No	No	No
seafood	Yes	No	No	No

As nouns, seafood is a hypernym of whitefish; that is, seafood is a word with a broader meaning than whitefish:

whitefish: any market fish--edible saltwater fish or shellfish--except herring
seafood: edible fish (broadly including freshwater fish) or shellfish or roe etc

whitefish (noun)	seafood (noun)
silvery herring-like freshwater food fish of cold lakes of the Northern Hemisphere	edible fish (broadly including freshwater fish) or shellfish or roe etc
flesh of salmon-like or trout-like cold-water fish of cold lakes of the Northern Hemisphere
any market fish--edible saltwater fish or shellfish--except herring