Can someone explain NVMe to me? The 4x PCIe lanes doesn't

SSD into the expansion slot PCI-Express Gen4x4 supported NVMe SSD Storage space, 250 GB

2 slot is just a plain x4 slot, they look exactly the same to the host The only way you can know for sure is if you have an slot already or

pcie 20 x16 slot 2 slot You can see two standard slots on the PCB, between the PCIe slots These have the mounting holes for horizontally mounting

pcie m2 slot Dual 221102280 PCIe NVMe SSD expansion card ; Bracket, Low-profile Low-profile flat and Full-height brackets are also included