Agree with above.
Orthopedic literally means ortho-pedic, straight-children. They founded scoliosis surgery. Orthos are good at bone work and alignment. But the difference between ortho spine and neurosurgery spine surgeons is obvious in the first imaging study ordered. They look at X-rays for bony alignment. We look at MRIs for nerve or cord impingement first. They spend the rest of their residency doing joints and fractures. All bloody work. We spend the rest of our residency dissecting aneurysms and resecting tumors. We bring that level of care to the spine.
That can be good and bad. I know orthos that zip through spine cases, and neuros who take more time. But you can find efficiency on both sides.
Neuros spend 50-70% of their residency on the spine. Orthos spend 10-20%. That's why they do fellowships. But the market is sometimes looking for "fellowship-trained" spine surgeons, so some neuros do fellowships for that reason as well. Many neurosurgery programs are moving to a model where their 12-month elective time is during PGY7, so you can do a fellowships, possibly CAST-accredited, during that year and save yourself a year of life.