There are multiple different types of practice options that dictate income, independence and sometimes quality of care or access to resources. The terms given below are general and distinctions are becoming increasingly blurred.
Physician has independence to select hours, night call arrangements, hospitals, partners,etc.
Kaiser Foundation is an example. This is similar to the Group Model except that there may be multiple contractual arrangements. There may be incentives as noted above. This is probably the largest category of practitioners at the present time. This refers to a vertical integration with a system of health care services including hospital, chronic care facility, home care program, lab and radiology services, etc.