Watershed segmentation algorithms

Thank you so much for all the input, I am learning so much from this site.

I see that there are several watershed segmentation filter examples out there:

First, what is the difference between WatershedImageFilter and morphological Watershed filter? And in the latter example, it looks like that threshold is never applied to the filter, how does this work?

Lastly, I just want to segment undersegmented labels where the original 3D image has some local minima that I could potentially use as markers - is there a ITK example for the watershed with marker available?

Thank you very much!