butter-flower vs herb

butter-flower and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
butter-flower	Yes	No	No	No
herb	Yes	No	No	No

As nouns, herb is a hypernym of butter-flower; that is, herb is a word with a broader meaning than butter-flower:

butter-flower: any of various plants of the genus Ranunculus
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 butter-flower include herbaceous plant.

butter-flower (noun)	herb (noun)
any of various plants of the genus Ranunculus	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