There are lots of similarities between the two practices and lots of reasons why they're important. Practitioners of either kind of medicine are able to treat most common health conditions in adults, and these practitioners can become primary care physicians. However, the big difference is that family practitioners can treat anyone in a family, including children, whereas internal medicine doctors are specialists in treating adults and seniors, so these doctors treat these patients exclusively. There's another difference between the practices: internal medicine doctors can specialize in particular areas of healthcare for adults and seniors such as heart health. Because internal medicine doctors specialize in treating adults and seniors who commonly get chronic conditions, the doctors have been trained to treat these conditions very effectively.