Robinia viscosa vs locust tree

Robinia viscosa and locust tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Robinia viscosa	Yes	No	No	No
locust tree	Yes	No	No	No

As nouns, locust tree is a hypernym of Robinia viscosa; that is, locust tree is a word with a broader meaning than Robinia viscosa:

Robinia viscosa: small rough-barked locust of southeastern United States having racemes of pink flowers and glutinous branches and seeds
locust tree: any of various hardwood trees of the family Leguminosae

Other hypernyms of Robinia viscosa include locust.

Robinia viscosa (noun)	locust tree (noun)
small rough-barked locust of southeastern United States having racemes of pink flowers and glutinous branches and seeds	any of various hardwood trees of the family Leguminosae