Hemiptera vs class Hexapoda

Hemiptera and class Hexapoda both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hemiptera	Yes	No	No	No
class Hexapoda	Yes	No	No	No

Hemiptera (noun)	class Hexapoda (noun)
plant bugs, bedbugs, some true bugs; also includes suborders Heteroptera (true bugs) and Homoptera (e.g., aphids, plant lice and cicadas)	insects; about five-sixths of all known animal species