PAs can do a lot of the same things that physicians do, and are of vital importance but are distinct from physicians. For one, physicians in the US complete 4 years of medical school, then a residency, and then possibly a fellowship. On the other hand a PA is generally done in 3 years, total.

Additionally PAs can prescribe many drugs in most states, but the supervising physician is ultimately responsible for the patients care.

Finally there are numerous subspecialties that simply aren’t available to PAs.