class Aves vs order Apterygiformes

class Aves and order Apterygiformes both are nouns.

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

class Aves (noun)	order Apterygiformes (noun)
(ornithology) the class of birds	a ratite bird order: flightless ground birds having vestigial wings and long bills and small eyes: kiwis