"There isn't a difference," Seimei answers, his tone surprisingly curt. He takes a deep breath, drags his hand down his face, and bows apologetically. "Please forgive me, Ysalwen, I did not mean to snap at you. But this touches on a matter of great concern for me."

'Concern' is an understatement.

"Every religion has certain esoteric knowledge and practices, not just for propitiating the gods but for calling on them to do specific things, or reading their will in natural phenomena. These esoteric practices would usually be performed by people with proper credentials - priests, monks, shamans...or onmyoji. And such practices were magic. They were not acts of worship, but belonged to religion nonetheless."