kingcup vs buttercup

kingcup and buttercup both are nouns.

Word	Noun	Adjective	Verb	Adverb
kingcup	Yes	No	No	No
buttercup	Yes	No	No	No

As nouns, kingcup and buttercup are synonyms defined as:

Other synonyms of kingcup include butter-flower, butterflower, crowfoot, goldcup.

kingcup (noun)	buttercup (noun)
any of various plants of the genus Ranunculus	any of various plants of the genus Ranunculus
swamp plant of Europe and North America having bright yellow flowers resembling buttercups