class Aves vs Craniata

class Aves and Craniata both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Aves	Yes	No	No	No
Craniata	Yes	No	No	No

class Aves (noun)	Craniata (noun)
(ornithology) the class of birds	fishes, amphibians, reptiles, birds, mammals