herba impia vs filago

herba impia and filago both are nouns.

Word	Noun	Adjective	Verb	Adverb
herba impia	Yes	No	No	No
filago	Yes	No	No	No

As nouns, filago is a hypernym of herba impia; that is, filago is a word with a broader meaning than herba impia:

herba impia: (literally an undutiful herb) a variety of cotton rose
filago: any plant of the genus Filago having capitate clusters of small woolly flower heads

Other hypernyms of herba impia include cotton rose, cudweed.

herba impia (noun)	filago (noun)
(literally an undutiful herb) a variety of cotton rose	any plant of the genus Filago having capitate clusters of small woolly flower heads