wood sorrel vs herb

wood sorrel and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
wood sorrel	Yes	No	No	No
herb	Yes	No	No	No

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

wood sorrel: any plant or flower of the genus Oxalis
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 wood sorrel include herbaceous plant.

wood sorrel (noun)	herb (noun)
any plant or flower of the genus Oxalis	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