Is there a difference by wiring the capacitors before or after the unit you're powering?
Do you mean related to the schematics or a real life situation?
In the schematics it does not matter. In real life - the rule is to connect the capacitors as close as possible to the unit you power.
PS: the reason to have the decoupling capacitors is to compensate "large" impedance of the wires (Z=R+jX). When you place the capacitor before the unit, there will be a "wire impedance" inserted from the capacitors to the unit (weak decoupling), when the capacitors will be connected after the unit, there will be the wire impedance inserted between the unit to the capacitors - that eliminates the blocking effect of the capacitors.
If the wires would not have any impedance (Z=0+j0) you would not need any decoupling capacitors.