pufferfish vs saltwater fish

pufferfish and saltwater fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
pufferfish	Yes	No	No	No
saltwater fish	Yes	No	No	No

As nouns, saltwater fish is a hypernym of pufferfish; that is, saltwater fish is a word with a broader meaning than pufferfish:

pufferfish: delicacy that is highly dangerous because of a potent nerve poison in ovaries and liver
saltwater fish: flesh of fish from the sea used as food

pufferfish (noun)	saltwater fish (noun)
any of numerous marine fishes whose elongated spiny body can inflate itself with water or air to form a globe; several species contain a potent nerve poison; closely related to spiny puffers	flesh of fish from the sea used as food
delicacy that is highly dangerous because of a potent nerve poison in ovaries and liver