class Aves vs order Psittaciformes

class Aves and order Psittaciformes both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Aves	Yes	No	No	No
order Psittaciformes	Yes	No	No	No

class Aves (noun)	order Psittaciformes (noun)
(ornithology) the class of birds	an order of birds including parrots and amazons and cockatoos and lorikeets and lories and macaws and parakeets