Under Advanced, Optional Destinations you can specify where the call is sent if it is not answered. Under FindMe/FollowMe you can do more or less the same thing.
Can someone explain to me in a simple way what the difference is and in which case which option is better used? Thank you in advance.
The main difference is that the phone user controls when FMFM is enabled and where the call goes vs. the optional destinations are admin settings beyond user control.