Are the leaves 1–2" long, rough on top and bottom, and the fruit nearly black when mature?
CLUE: This tree is native to the Southwest from Arizona to western Texas and southern Oklahoma.

Are the leaves over 2½" long and sometimes hairy but not rough on leaf undersurface? Fruit white, pink, or dark purple when mature.
CLUE: These trees are native or naturalized in the eastern half of the U.S.