class Aves vs order Insessores

class Aves and order Insessores both are nouns.

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

class Aves (noun)	order Insessores (noun)
(ornithology) the class of birds	a bird with feet adapted for perching (as on tree branches); this order is now generally abandoned by taxonomists