Are you confused between an orthopedic surgeon and a neurosurgeon? The orthopedic and neurosurgeon are both extensively trained and qualified to perform most types of spinal surgery.
An orthopedic surgeon is more than likely to have carried out fellowship training in orthopedic spine surgery and a neurosurgeon in neurosurgical spine surgery, most of the residency training is similar for both specialties.
The qualifications of the surgeon to do spine surgery are more driven by the amount of training in spine surgery and the amount of the surgeon's practice devoted to spine surgery (for example, vs. brain surgery for neurosurgeons, or vs. hip surgery for orthopedic surgeons), rather than by whether or not the surgeon is a neurosurgeon or orthopedic surgeon.
In some specific instances, either a neurosurgeon or an orthopedic spine surgeon may be the more appropriate choice. For example, an orthopedic surgeon is more capable of doing spine deformity surgery (such as surgery for scoliosis and other large spinal deformities), whereas a neurosurgeon can better treat intradural tumors, i.e. tumors that are inside the central nervous system.