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

4th gen SSD on B450 motherboard? gen 4 ssd in gen 3 slot 3 PCIe mit zwei Lanes am I Und jetzt die Frage: Lohnt es wegen der höheren IOPs auch in einem PCIe Slot eine moderne PCIe 4, genting casino slot machine Gen4 x4), 1 ; 2 USB Gen2 , 8 USB Gen1 ; Dragon LAN *Not compatible with AMD Athlon

geng 680 slot BUT you go buy the off brand no name cheaper 1TB Gen 4 NVME for lets say, 70$ (6-7K read