What is the difference between a neurosurgeon and an orthopedic surgeon when dealing with back pain?

Very little: I would choose based on the statistics of the individual surgeon rather than on the speciality.

Both are ok: Both neurosurgeons and fellowship trained orthopaedic surgeons treat spinal disorders. It is worth your time to learn about your surgeon before considering surgery. Hopefully, your primary care doctor can help to point you in the right direction. The most important thing to do is to make sure that the surgeon you choose has expertise in treating your problem. Neuro also does brain surgery.