That's a pretty common argument, but really holds zero water.
Yes, both Podiatrists and FA Ortho does surgery on feet, prescribes medications, sees foot clinic, etc. So yes, with regards to feet there is "little difference" between the two.
But as you defend podiatry, please do not inadvertently denigrate FA Ortho. Remember that these surgeons are fully Board Certified Orthopaedic Surgeons who can, and do, operate on every facet of the musculoskeletal system. While some of the more successful FA Ortho guys will have "foot only" practices, many others (if not most) will also see trauma, do basic scopes, occassionally some joint replacements, and manage fractures in most bones of the body. In addition, they are also MDs, meaning that they have completed medical school and a somewhat general internship where they cared for the spectrum of medical and surgical patients competently.
I'm not trying to put down Podiatrists, who are great at what they do. But an FA Orthopod is an Orthopaedist and Physician first, with subspecialty training in Foot & Ankle surgery as an add-on. Saying that the two are basically the same, is like saying a nurse is just like a doctor, since both know how to start IVs.