celery root vs herb

celery root and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
celery root	Yes	No	No	No
herb	Yes	No	No	No

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

celery root: grown for its thickened edible aromatic 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 celery root include herbaceous plant.

celery root (noun)	herb (noun)
thickened edible aromatic root of a variety of celery plant	aromatic potherb used in cookery for its savory qualities
grown for its thickened edible aromatic root	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests