The breadcrumb coating excluded from traditional tempura is panko.
Tempura uses a light batter, typically made from flour, egg, and cold water, rather than a layer of breadcrumbs. Ingredients such as shrimp, fish, eggplant, or shiso are dipped in the thin batter and briefly fried, producing a pale, airy, crisp shell.
Panko is a Japanese-style breadcrumb used for a different family of fried foods. It is especially associated with yōshoku, or Western-influenced Japanese cooking, including tonkatsu, korokke, and ebi furai. Those foods have a more substantial, craggy crust than classic tempura.
A common mix-up comes from restaurants or home cooks using panko to create extra crunch. That preparation may be delicious, but it is breaded frying rather than traditional tempura. The distinction is the coating method: batter for tempura, breadcrumbs for panko-coated dishes.