herbaceous plant vs herb

herbaceous plant and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
herbaceous plant	Yes	No	No	No
herb	Yes	No	No	No

As nouns, herbaceous plant and herb are synonyms defined as:

herbaceous plant and herb: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests

herbaceous plant (noun)	herb (noun)
a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests	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