class Aves vs superorder Ratitae

class Aves and superorder Ratitae both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Aves	Yes	No	No	No
superorder Ratitae	Yes	No	No	No

class Aves (noun)	superorder Ratitae (noun)
(ornithology) the class of birds	used in former classifications to include all ratite bird orders