What is the difference between epidural cortisone injections and epidural steroid injection?

None: Cortisone is a corticosteriod, but is no commonly used in esi treatment.

Cortisone is steroid: Cortisoneis a steroid but not one that we use often (if ever) for injection in the epidural space.

Well: Technically no difference, they are probably the same. Cortisone is a generic term for steroid, but likely another steroid will be used for the injection like dexamethasone, betamethasone, triamcinolone or methylprednisolone.