What is the difference between PCIe Gen 3 and PCIe Gen 4?

In ASUS 「PCIe x16 Slots - 7」

your i5-3470 works on PCIe natively, Optiplex 7010 has only one slot bound to CPU PCIe, others are linked via chipset

slot milling cutter PCIe compatibility and performance generates a LOT of confusion In Explaining PCIe Slots

slot garuda999 PCIe x16: This is the largest PCIe slot with 16 data lanes PCIe x16 slots are associated with graphics cards and provide the highest bandwidth