comfrey vs herb

comfrey and herb both are nouns.

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

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

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

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

comfrey: perennial herbs of Europe and Iran; make rapidly growing groundcover for shaded areas
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 comfrey include herbaceous plant.

comfrey (noun)	herb (noun)
leaves make a popular tisane; young leaves used in salads or cooked	aromatic potherb used in cookery for its savory qualities
perennial herbs of Europe and Iran; make rapidly growing groundcover for shaded areas	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests