class Aves vs order Galliformes

class Aves and order Galliformes both are nouns.

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

class Aves (noun)	order Galliformes (noun)
(ornithology) the class of birds	pheasants, turkeys, grouse, partridges, quails, chickens, brush turkeys, curassows, hoatzins