turnip-rooted celery vs herb

turnip-rooted celery and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
turnip-rooted celery	Yes	No	No	No
herb	Yes	No	No	No

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

turnip-rooted celery: 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 turnip-rooted celery include herbaceous plant.

turnip-rooted celery (noun)	herb (noun)
grown for its thickened edible aromatic 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