How are the options for working with the selection Smooth and Feather located in the Select -> Modify menu different from each other?

Question

Adobe Photoshop

I can not surprise the fundamental difference in their work, but I would very much like to understand it. Please advise if possible with examples.

Answer 1

Feather - smoothes by penetrating into the selection object.
Smooth - simply smoothes the corners of the selection.
It will be clearest to do the procedure on the same figures with the same settings and apply a mask to them.