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

Cortisone is steroid. Cortisoneis a steroid but not one that we use often (if ever) for injection in the epidural space.
None. Cortisone is a corticosteriod, but is no commonly used in esi treatment.
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.