burdock vs clotbur

burdock and clotbur both are nouns.

Word	Noun	Adjective	Verb	Adverb
burdock	Yes	No	No	No
clotbur	Yes	No	No	No

As nouns, burdock and clotbur are synonyms defined as:

burdock and clotbur: any of several erect biennial herbs of temperate Eurasia having stout taproots and producing burs

burdock (noun)	clotbur (noun)
any of several erect biennial herbs of temperate Eurasia having stout taproots and producing burs	any of several erect biennial herbs of temperate Eurasia having stout taproots and producing burs