On a plane that has SAFE Select, with SAFE self-level being one of the three flight modes and AS3X being the other two flight modes, there is no difference in the AS3X modes.
A Spektrum receiver in a real model has at least three flight modes, but SAFE Select was designed to only offer two of them - SAFE On and SAFE Off - for simplicity. That real receiver also has two of the three flight modes set the exact same way with AS3X only to be SAFE Off mode.
