healing herb vs herb

healing herb and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
healing herb	Yes	No	No	No
herb	Yes	No	No	No

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

healing herb: leaves make a popular tisane; young leaves used in salads or cooked
herb: aromatic potherb used in cookery for its savory qualities

healing herb (noun)	herb (noun)
leaves make a popular tisane; young leaves used in salads or cooked	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