What is the Difference Between PCIe Gen 3 & Gen 4?

Should I Buy a Gen 4 SSD for My Gen 3 Laptop? nvme gen 4 in gen 3 slot Testing and installing a Gen4 NVME SSD on a Gen3 Motherboard This includes Unboxing nvme in pcie slot Gen4 x4), 1 ; 2 USB Gen2 , 8 USB Gen1 ; Dragon LAN *Not compatible with AMD Athlon

nvme m2 slot motherboard The card physically has an X4 interface, so it could be plugged into an X4, X8, or X16 slot It can still physically only access 4 lanes (else