Difference Between MoP and Mop Safe

I usually find that this helps.

Any questions?

Please download the PDF manuals of your drive and search them for MoP (software-implemented Motor Potentiometer emulation). The MoP Safe refers to the safety integrated functions (STO, etc.).

If you don't require safety functions you don't have to worry about and if you require SIL 3 / PL e (i.e. traditional industrial SIL 3, not one of the more recent confusing SIL flavors) compliant controls you better know what you do as like ATEX it's something not very simple which can't be explained online in a forum.

As I know ABB drives much better than the Siemens ones I'd have to check the documentation too, so I can't help you much without looking up the details.