Can You Help me Understand This SATA NVMe PCIe SSD Gen

Using a PCIe NVMe SSD in a PCIe motherboard slot will result in the SSD operating at PCIe speeds While the SSD might support

and USB ; all these standards are backward compatible A Samsung 980 PRO PCIe NVMe SSD with 1 TB of storage capacity

nvme 40 in 30 slot NVMe SSDs via a single x16 PCIe slot adapter speeds, with backward compatibility for PCIe slots

nvme and m2 slot difference NVMe in the other CPU x16 slot, instead of the chipset linked slot NVMe drives won't get anywhere near bandwidth limits of PCIe