silky willow vs Sitka willow

silky willow and Sitka willow both are nouns.

Word	Noun	Adjective	Verb	Adverb
silky willow	Yes	No	No	No
Sitka willow	Yes	No	No	No

As nouns, silky willow and Sitka willow are synonyms defined as:

silky willow and Sitka willow: small shrubby tree of western North America (Alaska to Oregon)

Other synonyms of silky willow include Salix sitchensis.

silky willow (noun)	Sitka willow (noun)
North American willow with greyish silky pubescent leaves that usually blacken in drying	small shrubby tree of western North America (Alaska to Oregon)
small shrubby tree of western North America (Alaska to Oregon)