bur marigold vs burr marigold

bur marigold and burr marigold both are nouns.

Word	Noun	Adjective	Verb	Adverb
bur marigold	Yes	No	No	No
burr marigold	Yes	No	No	No

As nouns, bur marigold and burr marigold are synonyms defined as:

bur marigold and burr marigold: any of several plants of the genus Bidens having yellow flowers and prickly fruits that cling to fur and clothing

Other synonyms of bur marigold include beggar's-ticks, beggar-ticks, sticktight.

bur marigold (noun)	burr marigold (noun)
any of several plants of the genus Bidens having yellow flowers and prickly fruits that cling to fur and clothing	any of several plants of the genus Bidens having yellow flowers and prickly fruits that cling to fur and clothing