The Canon 5D Mark III has dual memory card slots that hold one CompactFlash (CF) format memory card and one Secure Digital (SD) format memory card. CF cards are faster than SD cards and perform better for video.
The Nikon D500 has 1 x XQD plus one 1 x SD memory card slot. The SD supports UHS-II speed which is great news since they offer faster-writing speed. We also recommend you to take a look at even more quick XQD memory cards.