laurel willow vs willow tree

laurel willow and willow tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
laurel willow	Yes	No	No	No
willow tree	Yes	No	No	No

As nouns, willow tree is a hypernym of laurel willow; that is, willow tree is a word with a broader meaning than laurel willow:

laurel willow: European willow tree with shining leathery leaves; widely naturalized in the eastern United States
willow tree: any of numerous deciduous trees and shrubs of the genus Salix

Other hypernyms of laurel willow include willow.

laurel willow (noun)	willow tree (noun)
European willow tree with shining leathery leaves; widely naturalized in the eastern United States	any of numerous deciduous trees and shrubs of the genus Salix