herb vs vascular plant

herb and vascular plant both are nouns.

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

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

herb: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests
vascular plant: green plant having a vascular system: ferns, gymnosperms, angiosperms

Other hypernyms of herb include tracheophyte.

herb (noun)	vascular plant (noun)
aromatic potherb used in cookery for its savory qualities	green plant having a vascular system: ferns, gymnosperms, angiosperms
a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests