What's the difference between ISOs and NSOs? Although there are some key differences to be aware of, non-qualified and incentive stock options also have a lot in common. For employees, stock options can offer both risk and reward. Unlike restricted stock units, which are given or "awarded" to employees, incentive stock options and non-qualified stock options must be purchased. Before you exercise your options, it is essential to understand how stock options work and how it may impact your tax situation.