It'd be helpful to know that they aren't billed the same!
From CMS:
> When an emergency department E/M is shared between a physician and a PA or NP from the same group practice and the physician provides the substantive portion of the E/M encounter with the patient, then the service may be billed under either the physician's or the PA's or NP’s UPIN/PIN number. If the physician does not provide the substantive portion of the encounter even if the physician participated in the service by reviewing the patient’s medical record, then the service may only be billed under the PA's or NP’s UPIN/PIN. In this scenario payment will be made at 85 percent of the Medicare physician fee schedule.