what counts as a distro

With that recent post about chrome os not counting as a distro of linux. It does bring a good question, what is a distro of linux?

If Linux is just a kernel then android and chrome os are Linux. Bur no really considers android a distro of linux. So linux is more then a kernel.

KDE say that neon is not a distro but doesn't really why neon is not but kubuntu is.