What are the differences between primary care doctors like family medicine, internal medicine and general practice.?

Their training. General practice usually means the doctor has completed only an internship (1 year) of hospital training after medical school. Family physicians and internal medicine doctors usually complete 3-4 years of further training after medical school and they take exams to become board certified in their specialties. All three may take care of some of the same problems, but their training is different.
Training and scope. Primary care docs include physicians who completed training in family medicine, pediatrics, internal medicine (or for some of us both internal medicine and pediatrics). This training is after 4 yrs of med school and at least 3 yrs long. In general, pediatricians care for infants to young adults, internists care for adults and family med and med/peds docs care for all ages.