evening primrose vs herb

evening primrose and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
evening primrose	Yes	No	No	No
herb	Yes	No	No	No

As nouns, herb is a hypernym of evening primrose; that is, herb is a word with a broader meaning than evening primrose:

evening primrose: any of several plants of the family Onagraceae
herb: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests

Other hypernyms of evening primrose include herbaceous plant.

evening primrose (noun)	herb (noun)
any of several plants of the family Onagraceae	aromatic potherb used in cookery for its savory qualities
	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests