pepper tree vs genus Kirkia

pepper tree and genus Kirkia both are nouns.

Word	Noun	Adjective	Verb	Adverb
pepper tree	Yes	No	No	No
genus Kirkia	Yes	No	No	No

pepper tree (noun)	genus Kirkia (noun)
small African deciduous tree with spreading crown having leaves clustered toward ends of branches and clusters of creamy flowers resembling lilacs	small genus of tropical South African trees and shrubs
small Peruvian evergreen with broad rounded head and slender pendant branches with attractive clusters of greenish flowers followed by clusters of rose-pink fruits