ER Physician billing

What is the difference in ER physician billing whether the physician is employed versus contracted with the hospital?

re: ER Physician billing

Could you be more specific, I am not sure what exactly you are asking about? From a CPT® standpoint, there is none. They will use the same codes.
Most ER physicians are contracted (belong to outside companies), and do their own billing of the visit codes and any procedures, while the hospital bills for supplies, etc.