The main difference is the triggering of a keystroke:
Cherry-MX
When pressed, a metal part held in flex is released, which makes contact until the key is back up and pushes the metal part back. https://www.cherrymx.de/en...
Corsair OPX
When pressed, a pin interrupts a light barrier and thus triggers the keystroke until the pin is out of the light barrier again: https://cwsmgmt.corsair.com/landing...

Both are pushed upwards by a spring. The resistance is the same for both (45g).

The Cherry switches release 0.2(!) mm later and can be pressed 0.2 mm further. Therefore, they may be (imperceptibly) slower, but (imperceptibly) more forgiving if a key is touched unintentionally.
These differences are probably within tolerances.
Both are extremely fast compared to other keyboards.

MX switches have worked reliably for years, and are dirt and dust resistant. Optical switches are relatively new and not very common, and I can imagine that dirt or dust once it has reached the bottom of the switch will permanently trigger it and make it unusable, whereas the contact in the MX switch virtually cleans itself. In addition, the light barrier requires other electronic parts that are probably more sensitive than the 2 metal parts in the MX switch.

I would buy the MX switches, but not this keyboard again, because:
too expensive
terrible ping noise

If you want optical switches, I would have a look here:
https://steelseries.com/gaming-key...
These switches are not triggered when a horizontal barrier is broken, but constantly measure the position of the key from below. This has the advantage that the trigger point can be variably adjusted, which in my opinion offers a clear advantage over the mechanical switch.
However, you will probably adjust it a few times and then leave it where it was comfortable.