white mullein vs mullein

white mullein and mullein both are nouns.

Word	Noun	Adjective	Verb	Adverb
white mullein	Yes	No	No	No
mullein	Yes	No	No	No

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

white mullein: densely hairy Eurasian herb with racemose white flowers; naturalized in North America
mullein: any of various plants of the genus Verbascum having large usually woolly leaves and terminal spikes of yellow or white or purplish flowers

Other hypernyms of white mullein include flannel leaf, velvet plant.

white mullein (noun)	mullein (noun)
densely hairy Eurasian herb with racemose white flowers; naturalized in North America	any of various plants of the genus Verbascum having large usually woolly leaves and terminal spikes of yellow or white or purplish flowers