It depends on whether the private practice attending has residents in terms of to what degree the two are different. However, in general academic surgeons make significantly less money, are university employees of a sort, and spend more time on research and education. Usually the university takes the surgeon's fees and gives the surgeon a portion of them as a salary. While private practice attendings spend more time operating, and eat what they kill, as in make all the money from those surgeries. However, you will find many private practice attendings who also take part in research and train residents, especially at the larger more academic private hospitals with orthopaedic programs.
