That’s position-dependent. In one case you might be in a totally closed position where there’s no obvious way forward and your position gradually deteriorates.

That’s position-dependent. In one case you might be in a totally closed position where there’s no obvious way forward and your position gradually deteriorates. In another case you might be in an ultra-sharp, open position where you miss some crazy sacrifice combination that leads to mate-in-10. The first example is clearly a strategic defeat and the second a tactical defeat. But calling it a “blunder” to miss the sacrifice in such a sharp position feels unfair. You might have been walking a tightrope for a long time to reach that point and then made one little slip any grandmaster could be expected to make.