pussy willow vs Salix discolor

pussy willow and Salix discolor both are nouns.

Word	Noun	Adjective	Verb	Adverb
pussy willow	Yes	No	No	No
Salix discolor	Yes	No	No	No

As nouns, pussy willow and Salix discolor are synonyms defined as:

pussy willow and Salix discolor: small willow of eastern North America having greyish leaves and silky catkins that come before the leaves

pussy willow (noun)	Salix discolor (noun)
small willow of eastern North America having greyish leaves and silky catkins that come before the leaves	small willow of eastern North America having greyish leaves and silky catkins that come before the leaves
much-branched Old World willow having large catkins and relatively large broad leaves