This is why I think seeing actual benchmarks will help.The Samsung 850 EVO 500GB would be actually be faster than the Apple SM0512G in this case because it has a better 4K Random Read.
We all can throw out various specs, and say how one is better then other, but how is it in actual usage. I stand by my opinion (not grounded in any sort of scientific testing) is most people will probably not even notice if its a Samsung or Apple