Differential aileron isn't really sound byte simple.

Symmetrical wings don't respond the way cambered wings react. Different airfoils react differently from each other.

The aileron moving up reduces lift almost always. And that reduces drag. But then it often starts to produce lift in the other direction. And that starts to create drag. So the wing on that side has lost drag and then starts to gain drag.

Aerodynamics is seldom sound byte simple.