Depending on the circles with which you are running, both can refer to people with MD's who do some sort of research and who also may teach at med schools. In general, I think that physician scientists are those MD's who may or may not also have PhD's and who do research most of the time (usually basic science) and do little to no clinical work (seeing patients) and may or may not teach. Academic physicians, in general, work or are associated with medical schools and/or large medical institutions, where they have clinical (seeing patients), research (basic science and/or clinical research), and oftentimes, teaching responsibilities (to medical students and/or residents). Key words: scientist=deals with science; academic (academia)=learning and/or teaching.