Naive optimism assumes things will turn out well regardless of effort or evidence. Realistic optimism is a different, more useful posture: a genuine belief that a good outcome is possible, paired with a clear-eyed assessment of the obstacles standing between here and there, and an honest accounting of what it will actually take to close that distance.
The distinction matters because naive optimism tends to collapse the moment reality disagrees with it, leaving a person unprepared and sometimes worse off for having ignored the warning signs. Realistic optimism, because it never pretended the obstacles were not there, tends to hold up better under pressure.
In practice it looks less like relentless positivity and more like steady planning: acknowledging a genuine risk, preparing for it, and still expecting, on balance, that the effort is worthwhile. That combination, hope with its eyes open, tends to outlast optimism that depends on nothing going wrong.