When raw speed actually matters
Sequential speed makes the biggest difference when you copy very large files, work with video caches, or load huge datasets. For gaming and everyday use, the gap between a 7,000 MB/s PCIe 4.0 drive and a 14,700 MB/s PCIe 5.0 drive like the Samsung 9100 Pro is hard to notice, because load times are limited by the CPU and software long before the SSD.
PCIe 5.0 needs the right slot and cooling
A PCIe 5.0 drive only reaches its rated speed in a PCIe 5.0 M.2 slot, found on newer AMD AM5 and Intel motherboards. In an older slot it still works, at PCIe 4.0 speed. PCIe 5.0 drives also run hotter, so use the motherboard's M.2 heatsink or a drive with a heatsink fitted.