Huntingdon willow vs willow

Huntingdon willow and willow both are nouns.

Word	Noun	Adjective	Verb	Adverb
Huntingdon willow	Yes	No	No	No
willow	Yes	No	No	No

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

Huntingdon willow: large willow tree of Eurasia and North Africa having greyish canescent leaves and grey bark
willow: any of numerous deciduous trees and shrubs of the genus Salix

Other hypernyms of Huntingdon willow include willow tree.

Huntingdon willow (noun)	willow (noun)
large willow tree of Eurasia and North Africa having greyish canescent leaves and grey bark	a textile machine having a system of revolving spikes for opening and cleaning raw textile fibers
	any of numerous deciduous trees and shrubs of the genus Salix