I understand that both are correct; ailerons cause yaw and so does the tilting lift components due to roll.

The down aileron increases camber, increases lift and increases drag. The opposite is true; up aileron decreases camber, decreases lift and decreases drag. The delta in the drag causesthe yawing moment.

I don't know which one accounts for a greater percentage of yaw...ailerons or lift tilt...but I imagine there are other combinations and dependent variables.

Tom