tall white violet vs violet

tall white violet and violet both are nouns.

Word	Noun	Adjective	Verb	Adverb
tall white violet	Yes	No	No	No
violet	Yes	Yes	No	No

As nouns, violet is a hypernym of tall white violet; that is, violet is a word with a broader meaning than tall white violet:

tall white violet: tall North American perennial with heart-shaped leaves and white flowers with purple streaks
violet: any of numerous low-growing violas with small flowers

tall white violet (noun)	violet (noun)
tall North American perennial with heart-shaped leaves and white flowers with purple streaks	a variable color that lies beyond blue in the spectrum
	any of numerous low-growing violas with small flowers

tall white violet (adjective)	violet (adjective)
	of a color intermediate between red and blue