fern vs class Filicopsida

fern and class Filicopsida both are nouns.

Word	Noun	Adjective	Verb	Adverb
fern	Yes	No	No	No
class Filicopsida	Yes	No	No	No

fern (noun)	class Filicopsida (noun)
any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores	ferns