class Hexapoda vs order Phasmatodea

class Hexapoda and order Phasmatodea both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Hexapoda	Yes	No	No	No
order Phasmatodea	Yes	No	No	No

class Hexapoda (noun)	order Phasmatodea (noun)
insects; about five-sixths of all known animal species	in some classifications considered a suborder of Orthoptera: stick insects; leaf insects