pearly nautilus vs cephalopod

pearly nautilus and cephalopod both are nouns.

Word	Noun	Adjective	Verb	Adverb
pearly nautilus	Yes	No	No	No
cephalopod	Yes	Yes	No	No

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

pearly nautilus: cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions
cephalopod: marine mollusk characterized by well-developed head and eyes and sucker-bearing tentacles

Other hypernyms of pearly nautilus include cephalopod mollusk.

pearly nautilus (noun)	cephalopod (noun)
cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions	marine mollusk characterized by well-developed head and eyes and sucker-bearing tentacles

pearly nautilus (adjective)	cephalopod (adjective)
	relating or belonging to the class Cephalopoda