How can I identify the macOS version from the command line? After detecting a GNU/Linux system through running uname, in a GNU/Linux distribution lsb_release -a is a good entry level utility you could use to [try to] find out the GNU/Linux distribution name and particular version1.

After detecting a Darwin (possibly macOS) system through running uname, there must be a Different (maybe not that much...) way to Ask the OS version number1. Even if it only works on macOS, it'd be useful.

This is similar to the /etc/release for other Unix / Linux, but I’d like to specifically target macOS to script a check of the version. In what way(s) is this possible?
I don't know if all of this is imposed by Darwin, the manual page seems like it maybe is a Mac OS X (sic in my manual page as of Sep 2019) thing, but there is the awesome sw_vers:

$ sw_vers
ProductName:    Mac OS X
ProductVersion: 10.14.6
BuildVersion:   yadda yadda yadda
$ _