The term software distribution, according to wikipdedia, describes a bundle of a specific software (or a collection of multiple, even an entire operating system). Since a live CD must be bootable, with an operating system, the term distro does not apply here. Putting a software distro on a CD, such as Novell ZENworks, gives you Novell ZENworks on a CD, _not_ a live CD. Live CDs and live DVDs can also be fundamentally different than live USBs, which is why there are two different Wikipedia pages, one for CD/DVDs, and one for USBs.