Ssd sata and ssd nvme pcie slot compatibility

How to Add NVMe SSD to your Motherboard nvme gen 4 in gen 3 slot In comparison, PCIe Gen4 operates at 16 GTs, converting to about 2 GBs per PCIe lane PCIe Gen4 is the fourth generation of the PCI Express specification As nvme pcie 40 in 30 slot In comparison, PCIe Gen4 operates at 16 GTs, converting to about 2 GBs per PCIe lane PCIe Gen4 is the fourth generation of the PCI Express specification As

nvme vs m2 slot Looking at Amazon there is PCIe Gen 3 NVME and PCIe Gen 4 NVME for sale I don't see this even mentioned on the Wikipedia page for NVM Express