Aside from loops and more presets can anyone highlight major differences between these? I only have a few pedals I need to switch and midi control to switch my amp channels via the voodoo labs control switcher. Sorry if this was asked elsewhere. I found a used 4 button switcher so I thought about getting that instead of the 8.

The PX-8+ is itself a MIDI Controller as well as a loop switcher. So it has presets that will recall any of its own loops and send a MIDI command to control the Control Switcher.

The original 4-Loop Pedal Switcher is only a loop switcher. It needs a MIDI Controller to have presets. It will not recall presets or send MIDI commands to control the Control Switcher without a MIDI Controller.
For instance, the Voodoo Lab Commander that was launched with the original 4-Loop Pedal Switcher would work to control the Pedal Switcher and Control Switcher.

I hope that helps!