octopus vs seafood

octopus and seafood both are nouns.

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

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

octopus: tentacles of octopus prepared as food
seafood: edible fish (broadly including freshwater fish) or shellfish or roe etc

octopus (noun)	seafood (noun)
bottom-living cephalopod having a soft oval body with eight long tentacles	edible fish (broadly including freshwater fish) or shellfish or roe etc
tentacles of octopus prepared as food