dibranch vs cephalopod mollusk

dibranch and cephalopod mollusk both are nouns.

Word	Noun	Adjective	Verb	Adverb
dibranch	Yes	No	No	No
cephalopod mollusk	Yes	No	No	No

As nouns, cephalopod mollusk is a hypernym of dibranch; that is, cephalopod mollusk is a word with a broader meaning than dibranch:

dibranch: cephalopods having two gills
cephalopod mollusk: marine mollusk characterized by well-developed head and eyes and sucker-bearing tentacles

Other hypernyms of dibranch include cephalopod.

dibranch (noun)	cephalopod mollusk (noun)
cephalopods having two gills	marine mollusk characterized by well-developed head and eyes and sucker-bearing tentacles