Bravely Default and Bravely Second: End Layer Edit
There are three difficulty levels to choose from: Easy, Medium and Hard, which determine the enemies' stats and AI behavior. It is also possible to modify the rate of random encounters or disable them altogether, as well as disable Exp and JP gains at the end of battles, and even set destination markers to appear or not. All of these settings can be adjusted at any time (except mid-battle and cutscenes) in the Difficulty section of the Config menu.
For enemies the stat changes are as so:
Aim and Evade do change between difficulty levels, but are not calculated by multiplying the Normal value. Evade remains the same between Normal and Hard, and Easy is either the same as Normal or one less based on an unknown factor. Similarly Aim does not wildly differ between difficulties, having only a few points in between.