Chinese cinnamon is an evergreen tree whose fragrant bark supplies the cassia cinnamon commonly sold in U.S. stores. The spice in a jar labeled simply “cinnamon” may come from any of several kinds of cinnamon trees.
A whole cassia bark stick is thick and hard; Ceylon cinnamon forms many thin rolled layers. A photo of leaves alone may not settle the identification.
Why they get mixed upBoth are sold as cinnamon.