Some links are old.
The .x is a generic nomenclature to refer to all the various updates of that particular operating system. Generally, that's a good idea. You should never try to install a system older than the one that was installed on your hardware. New systems offer enhancements that some of us need, but they can plague us with more problems. These problems don't usually exist with the OS itself but with third-party commercial applications, hardware drivers, and shareware we install.