fugu vs sea squab

fugu and sea squab both are nouns.

Word	Noun	Adjective	Verb	Adverb
fugu	Yes	No	No	No
sea squab	Yes	No	No	No

As nouns, sea squab is a hypernym of fugu; that is, sea squab is a word with a broader meaning than fugu:

fugu: a blowfish highly prized as a delicacy in Japan but highly dangerous because the skin and organs are poisonous
sea squab: delicacy that is highly dangerous because of a potent nerve poison in ovaries and liver

Other hypernyms of fugu include blowfish, puffer, pufferfish.

fugu (noun)	sea squab (noun)
a blowfish highly prized as a delicacy in Japan but highly dangerous because the skin and organs are poisonous	delicacy that is highly dangerous because of a potent nerve poison in ovaries and liver