class Arachnida vs order Opiliones

class Arachnida and order Opiliones both are nouns.

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

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