false nettle vs herb

false nettle and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
false nettle	Yes	No	No	No
herb	Yes	No	No	No

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

false nettle: any of several flowering weeds of the genus Boehmeria lacking stinging hairs
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 false nettle include herbaceous plant.

false nettle (noun)	herb (noun)
any of several flowering weeds of the genus Boehmeria lacking stinging hairs	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