blue thistle vs blue devil

blue thistle and blue devil both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue thistle	Yes	No	No	No
blue devil	Yes	No	No	No

As nouns, blue thistle and blue devil are synonyms defined as:

blue thistle and blue devil: a coarse prickly European weed with spikes of blue flowers; naturalized in United States

Other synonyms of blue thistle include blueweed, Echium vulgare, viper's bugloss.

blue thistle (noun)	blue devil (noun)
a coarse prickly European weed with spikes of blue flowers; naturalized in United States	the sodium salt of amobarbital that is used as a barbiturate; used as a sedative and a hypnotic
	a coarse prickly European weed with spikes of blue flowers; naturalized in United States