What Is an Slot and What Devices Use the Slot?

2 drives will be NVME or SATA, that will have similar connectors on the end, but you will see that the groove opening is in a different spot

two NVME SSD It doesn't matter which slots they are put in, there is negligible performance difference

m2 expansion slot Won't matter much, but generally you want your OS on the fastest drive you have, or in the fastest slot you have The difference from 1 slot

m2 slot types 2 expansion card to add an additional Slot to your PC ATX motherboards have ample slots but if you have a small form factor mATX motherboard (usually