Output histograms are of the rendered output-referred data, as opposed to raw histograms which are of the unprocessed scene-referred data. For example, if you took your raw file and set the Exposure slider all the way to the right, making your image appear completely white, you'd expect the resulting "output histogram" to be bunched up all the way to the right, since it's reflecting the huge Exposure bump that you made. It would naturally appear very different from the original raw histogram which doesn't incorporate your adjustment.
I was referring to the difference between the adjusted
RAW histogram and the output histogram. What puzzles me is that even though the output histogram shows signficant clipping of shadows and highlights, I cannot see any difference between the output image and the adjusted RAW image