class Reptilia vs subclass Synapsida

class Reptilia and subclass Synapsida both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Reptilia	Yes	No	No	No
subclass Synapsida	Yes	No	No	No

class Reptilia (noun)	subclass Synapsida (noun)
class of cold-blooded air-breathing vertebrates with completely ossified skeleton and a body usually covered with scales or horny plates; once the dominant land animals	extinct reptiles of the Permian to Jurassic considered ancestral to mammals