class Reptilia vs Archosauria

class Reptilia and Archosauria both are nouns.

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

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