class Polyplacophora vs Mollusca

class Polyplacophora and Mollusca both are nouns.

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

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