PCIe vs PCIe NVMe SSDs: What's the difference?

My laptop has a gen 3 slot First of all, I know that a PCIe 4 SSD NVMe will be running at gen 3 speeds and bottlenecked by the PCIe 3 slot But

There seem to be some Gen 4 x4 NVMe 2230 M 1) The HAT is Gen 3 and I read that Gen 4 is backwards compatible, but at Gen 3 speeds Are Gen4 drives backwards

genie''s 3 wishes slot Solved: Does installing gen4 NVMe SSD on PCIe 3 slot affect the speed? or should i buy 3 gen3 NVMe ssd? Please give me some advice

genghis khan slot machine Questions about buying a gen 4 SSD NVMe for your Gen 3 laptop? Gen 3 or Gen 4 SSD is