pecopteris vs fern

pecopteris and fern both are nouns.

Word	Noun	Adjective	Verb	Adverb
pecopteris	Yes	No	No	No
fern	Yes	No	No	No

As nouns, fern is a hypernym of pecopteris; that is, fern is a word with a broader meaning than pecopteris:

pecopteris: Carboniferous fossil fern characterized by a regular arrangement of the leaflets resembling a comb
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

pecopteris (noun)	fern (noun)
Carboniferous fossil fern characterized by a regular arrangement of the leaflets resembling a comb	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores