knob celery vs celery root

knob celery and celery root both are nouns.

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

As nouns, knob celery and celery root are synonyms defined as:

knob celery and celery root: grown for its thickened edible aromatic root

Other synonyms of knob celery include Apium graveolens rapaceum, celeriac, root celery, turnip-rooted celery.

knob celery (noun)	celery root (noun)
grown for its thickened edible aromatic root	thickened edible aromatic root of a variety of celery plant
	grown for its thickened edible aromatic root