Is it possible to use the difference blend mode to create mask of the difference between layers?

hi.

I think what you are trying to achieve is not best done with the workflow (difference blend mode) that you're trying to adopt. Also, any difference you achieve will always require selection, choosing a blend mode will not automatically created selection. That said let me show you a better way of what you are trying to achieve, is little bit more advanced than simply choosing a blend mode...
Video to follow.