blue devil vs blue thistle

blue devil and blue thistle both are nouns.

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

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

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

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

blue devil (noun)	blue thistle (noun)
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
a coarse prickly European weed with spikes of blue flowers; naturalized in United States