Tiarella cordifolia vs herb

Tiarella cordifolia and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
Tiarella cordifolia	Yes	No	No	No
herb	Yes	No	No	No

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

Tiarella cordifolia: stoloniferous white-flowered spring-blooming woodland plant
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 Tiarella cordifolia include herbaceous plant.

Tiarella cordifolia (noun)	herb (noun)
stoloniferous white-flowered spring-blooming woodland plant	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