different pcie slots

Well, your graphics card doesn't have to be lonely since you can install a bunch of different PCIe cards into your motherboard's secondary PCIe slot!

SATA M.2 are different, most don't even fit in the same slot as the PCIe ones.

PCIe slots come in different physical configurations: x1, x4, x8, and x16. The number after x tells you how many lanes (how data travels to and from the PCIe card--more on that later) that the PCIe slot has.