Why is cilantro kosher for Passover when coriander isn’t?

Shalom! Actually they are exactly the same herb. Cuzbara= coriander=cilantro Often coriander is the dried spice version of it. So maybe that doesn't have the Passover hechsher on it... Many dried spices are used in machinery with kitniyos spices or sprayed with miniscule amounts of starch to be free flowing from shaker. All the best!