Is there any difference between using the "select and mask" option in select and the "mask" icon at the bottom? Would there be a reason or situation to use one and not the other? Or is one more of a short cut?
If you click the mask icon at the bottom of the Layers panel, now you have an empty mask that won't change unless you paint something in there yourself.
If you use Select and Mask, you can apply some automated tools, like click Select Subject to automatically figure out the subject and draw an initial selection around it for you, click Refine Hair to get a more detailed selection of hair near the selection edge, and all those other previewing aids and selection refinement tools and controls you see in there for tuning the selection edge until it’s as close to perfect as you can get it. (Instead of having to painfully and manually draw and paint a detailed mask from scratch.) And you can have it produce a finished layer mask at the end.