Neurosurgery cases tend to be longer and more tedious, whereas ortho and general cases vary from quick, routine 1-hour procedures to some very long involved cases. And neuro has patients with pretty severe problems that can't always be totally fixed no matter how much surgery you do, wheras ortho certainly has lots of fixable problems, and gereral seems to have more fixable problems than neuro as well. These may be some of your answers to why neuro has the reputation as a more stressful lifestyle, although hours are pretty similar and variable depending on where and how much you choose to work regardless of surgical specialty.