soap-weed vs soap tree

soap-weed and soap tree both are nouns.

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

As nouns, soap-weed and soap tree are synonyms defined as:

soap-weed and soap tree: tall arborescent yucca of southwestern United States

Other synonyms of soap-weed include soapweed, Yucca elata.

soap-weed (noun)	soap tree (noun)
tall arborescent yucca of southwestern United States	tall arborescent yucca of southwestern United States