A doctor (MD or DO) and a physician assistant (PA) can often do many of the same things in a clinical setting: diagnose conditions, order tests, prescribe medications, and manage treatment plans. The core difference is the depth and length of training. Doctors complete roughly 11 to 15 years of education and supervised training after college, while PAs typically finish in about 27 months of graduate school and can begin practicing immediately.
That training gap shapes everything else: how much autonomy each provider has, how they specialize, what they earn, and what your visit looks like as a patient.
Education and Training Hours
Both doctors and PAs learn medicine using the same “medical model,” meaning they study anatomy, pharmacology, disease processes, and clinical reasoning in similar ways. PA programs are often described as a condensed version of medical school, covering the same core subjects in a shorter timeframe.
The numbers, though, are substantially different. During medical school alone, MD and DO students complete approximately 5,700 hours of preclinical coursework and around 6,000 hours of clinical rotations. PA students complete roughly 2,000 clinical hours during their programs. After medical school, doctors enter residency training, which lasts three to seven years depending on the specialty. That residency adds thousands more supervised clinical hours before a physician can practice independently. PAs have optional postgraduate fellowships, but fewer than 5% pursue them.
All told, a physician who finishes a standard three-year residency will have accumulated well over 15,000 hours of clinical training. A PA enters practice with closer to 2,000.
Scope of Practice and Autonomy
Historically, PAs were required to practice under the supervision of a licensed physician. That arrangement is changing. A growing number of states have adopted what’s called “Optimal Team Practice,” which removes the legal requirement for a specific supervisory relationship between a PA and a physician. In these states, PAs collaborate with physicians as part of a team but don’t need a formal supervising doctor to see patients.
In states that still require supervision, the arrangement varies widely. Some mandate that a physician co-sign charts or be physically present in the building. Others allow PAs to work with a supervising physician available by phone. The day-to-day reality in many clinics and hospitals is that PAs function with significant independence, seeing their own patients and making clinical decisions, then consulting the supervising physician as needed.
Prescribing authority also depends on state law. PAs can prescribe medications, including controlled substances, in all 50 states, but the rules around certain drug categories (like opioids and stimulants) differ. Some states require additional oversight or limit which schedules a PA can prescribe. Physicians face no such restrictions beyond their DEA registration and state license.
How Specialization Works
This is one of the biggest practical differences between the two careers. Physicians specialize through residency and fellowship training, which locks in their focus early. A cardiologist who wants to switch to dermatology would essentially need to redo years of residency. The commitment is deep but narrow.
PAs are educated as medical generalists and recertify as generalists throughout their careers. A PA working in orthopedics can transition to emergency medicine or psychiatry without going back to school. They’ll need on-the-job training in the new specialty, but there’s no formal retraining or recertification process to navigate. This lateral mobility is unique to the PA profession and is one of its major selling points.
Compensation and Job Growth
The pay gap reflects the training gap. As of May 2024, the median annual salary for physician assistants was $133,260. For physicians and surgeons, the Bureau of Labor Statistics reports a median pay at or above $239,200 per year, with many specialties earning significantly more.
PA employment is projected to grow 20% from 2024 to 2034, which is far faster than average. The demand is driven by physician shortages, an aging population, and the cost-effectiveness of using PAs to handle a growing share of clinical work. For someone weighing the two career paths, PAs trade a lower salary ceiling for a shorter (and less expensive) educational investment and faster entry into the workforce.
What Changes for You as a Patient
If you’re seeing a PA instead of a doctor, your visit will often look and feel the same. The PA will take your history, examine you, order labs or imaging, make a diagnosis, and prescribe treatment. In many primary care offices, urgent care clinics, and specialty practices, PAs handle the majority of routine and moderately complex visits.
One behind-the-scenes difference involves how your visit is billed. Medicare reimburses PA services at 85% of the physician rate. So the same office visit billed under a PA’s name generates less revenue for the practice than one billed under a physician’s name. Some practices bill PA visits “incident to” a physician’s services (when the doctor is on-site and involved in the care plan), which allows reimbursement at the full physician rate. Private insurers have their own reimbursement structures, but the general pattern holds: PA visits cost the system slightly less.
For complex or unusual cases, surgical procedures, or situations requiring years of subspecialty expertise, you’ll typically see a physician. PAs are most common in primary care, urgent care, emergency departments, and surgical teams where they assist in the operating room and manage pre- and post-operative care. In many hospital settings, the PA is the provider you’ll interact with most frequently, with the attending physician overseeing the overall care plan.