subclass Archosauria vs class Reptilia

subclass Archosauria and class Reptilia both are nouns.

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

subclass Archosauria (noun)	class Reptilia (noun)
a large subclass of diapsid reptiles including: crocodiles, alligators, dinosaurs, pterosaurs, plesiosaurs, ichthyosaurs, thecodonts	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