Accountable Physician Practice
An Accountable Physician Practice is a multispecialty medical group or physician organization that strives to integrate and coordinate the work of a community of physicians and healthcare professionals to provide comprehensive outpatient services for patients. These healthcare professionals work in teams and are encouraged and supported by the organization’s work flow processes communications procedures, and payment systems to quickly and easily get patients the care they need when they need it. The Accountable Physician Practice is built on the multispecialty medical group model: teams of physicians skilled in a range of specialties who practice together. These groups include primary care doctors, specialists, health educators, nurses, dietitians, and all the other health professionals a patient might need to stay healthy.
Accountable Care Organization
Generally, an Accountable Care Organization can be defined as a set of healthcare providers — including primary care physicians, specialists, and hospitals — who work together and accept collective responsibility for the cost and quality of care delivered to a population of patients.  Unlike the “patient-centered medical home” (see definition below), ACOs would be accountable for the cost and quality of care both within and outside of the primary care relationship. As such, ACOs must include specialists and hospitals in order to be able to control costs and improve health outcomes across the entire care continuum. ACOs by nature would be larger than a single medical home or physician’s office. There are many known benefits of the ACO structure over the medical home model, including the ability to better manage the care for a greater population of people with a larger budget. Being able to use the dollars across a wider range of patients and conditions allows for better overall cost management, less variation within the population, and the ability to track and trend for quality.
Coordinated Care
When a person requires the services of more than one doctor and across multiple healthcare facilities or settings, organizing and coordinating all of the patient’s needs can become complex and burdensome for patients.  When  care providers work together and support one another, patients are better able to get the right care at the right time. The result of coordinated care is enhanced quality of care and quality of life. Patients receive coordinated care from an efficient integrated or organized delivery system, wherein medical resources are shared by and communication about treatment plans takes place between all care providers so that the best, most-informed medical decisions can be made on behalf of the patient.
Medical Home
The Patient-Centered Medical Home model was proposed by the American Academy of Family Physicians, American Academy of Pediatrics, American College of Physicians, and American Osteopathic Association in 2007. It is, in essence, an enhanced primary care delivery model that strives to achieve better access, coordination of care, prevention, quality, and safety within the primary care practice, and to create a strong partnership between the patient and primary care physician. Like accountable care organizations, the medical home model is referenced many times in the current Affordable Care Act as one way to improve health outcomes through care coordination.

The Accountable Care Organization is also based around a strong primary care core. But ACOs are comprised of many “medical homes”—in other words, many primary care providers and/or practices that work together. Some have even dubbed ACOs the “medical village.”

Organized Delivery System
An organized delivery system is a “network of organizations that provides or arranges to provide a coordinated continuum of services to a defined population and is willing to be held clinically and fiscally accountable for the outcomes and health status of the population served.”  — S. M. Shortell and others, Remaking Health Care in America: The Evolution of Organized Delivery Systems (San Francisco: Jossey-Bass, 1996), p. 7.