class Aves vs order Sphenisciformes

class Aves and order Sphenisciformes both are nouns.

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

class Aves (noun)	order Sphenisciformes (noun)
(ornithology) the class of birds	penguins