class Aves vs genus Protoavis

class Aves and genus Protoavis both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Aves	Yes	No	No	No
genus Protoavis	Yes	No	No	No

class Aves (noun)	genus Protoavis (noun)
(ornithology) the class of birds	extinct primitive birds of the Triassic period; 70 million years before archaeopteryx