soap-weed vs yucca

soap-weed and yucca both are nouns.

Word	Noun	Adjective	Verb	Adverb
soap-weed	Yes	No	No	No
yucca	Yes	No	No	No

As nouns, yucca is a hypernym of soap-weed; that is, yucca is a word with a broader meaning than soap-weed:

soap-weed: tall arborescent yucca of southwestern United States
yucca: any of several evergreen plants of the genus Yucca having usually tall stout stems and a terminal cluster of white flowers; warmer regions of North America

soap-weed (noun)	yucca (noun)
tall arborescent yucca of southwestern United States	any of several evergreen plants of the genus Yucca having usually tall stout stems and a terminal cluster of white flowers; warmer regions of North America