Armoracia rusticana vs herb

Armoracia rusticana and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
Armoracia rusticana	Yes	No	No	No
herb	Yes	No	No	No

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

Armoracia rusticana: coarse Eurasian plant cultivated for its thick white pungent root
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 Armoracia rusticana include herbaceous plant.

Armoracia rusticana (noun)	herb (noun)
coarse Eurasian plant cultivated for its thick white pungent root	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