genus Pecopteris vs fern genus

genus Pecopteris and fern genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Pecopteris	Yes	No	No	No
fern genus	Yes	No	No	No

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

genus Pecopteris (noun)	fern genus (noun)
genus of Carboniferous fossil ferns	genera of ferns and fern allies