plectognath fish vs order Plectognathi

plectognath fish and order Plectognathi both are nouns.

Word	Noun	Adjective	Verb	Adverb
plectognath fish	Yes	No	No	No
order Plectognathi	Yes	No	No	No

plectognath fish (noun)	order Plectognathi (noun)
tropical marine fishes having the teeth fused into a beak and thick skin covered with bony plates or spines	boxfishes, filefishes, globefishes, ocean sunfishes, triggerfishes, puffers