class Arachnida vs order Acarina

class Arachnida and order Acarina both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Arachnida	Yes	No	No	No
order Acarina	Yes	No	No	No

class Arachnida (noun)	order Acarina (noun)
a large class of arthropods including spiders and ticks and scorpions and daddy longlegs; have four pairs of walking legs and no wings	mites and ticks