blue thistle vs Echium vulgare

blue thistle and Echium vulgare both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue thistle	Yes	No	No	No
Echium vulgare	Yes	No	No	No

As nouns, blue thistle and Echium vulgare are synonyms defined as:

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

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

blue thistle (noun)	Echium vulgare (noun)
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