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

PCIE GPU on PCIE MOBO can i use pcie 3 0 in 2 0 slot So using the cards on PCI should be perfectly fine, I plan on using it as well Additionally, I also found benchmarks comparing RTX 3080 candy burst slot What is PCI express card? How many types of PCIe cards are there? What does PCIe x8, or PCIe x16 mean? Can I use a PCIe card in a slot?

candy paradise slot x, , , ) PCIe cards can always operate in PCIe slots with the same or more lanes than the card