class Polyplacophora vs phylum Mollusca

class Polyplacophora and phylum Mollusca both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Polyplacophora	Yes	No	No	No
phylum Mollusca	Yes	No	No	No

class Polyplacophora (noun)	phylum Mollusca (noun)
small class of marine mollusks comprising the chitons; sometimes considered an order of the subclass Amphineura	gastropods; bivalves; cephalopods; chitons