yellow star-thistle vs Barnaby's thistle

yellow star-thistle and Barnaby's thistle both are nouns.

Word	Noun	Adjective	Verb	Adverb
yellow star-thistle	Yes	No	No	No
Barnaby's thistle	Yes	No	No	No

As nouns, yellow star-thistle and Barnaby's thistle are synonyms defined as:

yellow star-thistle and Barnaby's thistle: European weed having a winged stem and hairy leaves; adventive in the eastern United States

Other synonyms of yellow star-thistle include Centaurea solstitialis.

yellow star-thistle (noun)	Barnaby's thistle (noun)
European weed having a winged stem and hairy leaves; adventive in the eastern United States	European weed having a winged stem and hairy leaves; adventive in the eastern United States