DL360 Gen10 PCIE Slot 3 not PCIE Compatible?

What is the Difference Between PCIe Gen 3 & Gen 4? pcie 3 slot An x4 PCIe device has a theoretical max transfer rate of MBsec according to wiki pcie 20 x1 slot An x4 PCIe device has a theoretical max transfer rate of MBsec according to wiki

pcie 30 x1 slot PCIe Slot Version