2 x Motherboard

The only difference is the way they connect to your motherboard--they utilize the PCIe slot instead of via an connector They also are much

2 SSD is keyed to prevent insertion of a card connector to an incompatible socket on the host The specification

slot scanner NVMe SSD to PCIe x4 Mobile RackBackplane wRemovable Tray for PCI Express Expansion Slot, Tool-less Installation, PCIe Hot-Swap Drive Bay

slot machne is a slot that can interface with SATA , PCI Express