Guinea grains vs herb

Guinea grains and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
Guinea grains	Yes	No	No	No
herb	Yes	No	No	No

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

Guinea grains: West African plant bearing pungent peppery seeds
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 Guinea grains include herbaceous plant.

Guinea grains (noun)	herb (noun)
West African plant bearing pungent peppery seeds	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