You could use a partition on an existing Linux system. That would be the same as using the temporary system. However, assuming you are using an empty system, you will need something to build the LFS software with. You can't just drop a compiler on a partition and start churning away. You need a little more than that. A kernel, for example, and a boat load of libraries :)
From the Linux distributions Wikipedia entry:
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions (often called distros for short) are Operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications.
What distinguishes them is the hardware they supposrt, packaging, kernel patches, what set and versions of applications they ship, their documentation, install methods etc. Other "classifications" are whether they are more oriented towards end users or servers.
Some of the distributions (Debian, Gentoo, Fedora and others) are used as a "starting point" for other distributions (Ubuntu is derived from Debian for instance). That means that the creators of for instance Sabayon Linux used a Gentoo distribution to start their development effort, and keep track of Gentoo's evolution to some extent.
You can look at the Distrowatch search page for this kind of examples.
"RPM-based" distributions is a different classification. RPM is a package management system, not a distribution. Some distributions use it (RedHat and Suse comes to mind) directly or via one of its frontends. Others use different systems (pacman for Arch, portage for Gentoo). The package management system is one of the important differences between distributions.
Regarding versions, there are no strict criteria. The distribution developers/managers decide on what versions/patches/new software they want to include in a new version, polish it, and when it's ready, they ship it. There isn't a consistent versioning scheme across distributions.
For your last question I'm not sure I understand, but you could say that Windows NT, 2000, XP, 2003/Vista, 2008 and Windows 7 are "versions" of the Windows "distribution". And they are all in the Windows NT family of Windows releases.
So if you want to draw a parallel with Linux distributions, yes, each windows "release" is closer to a version of a Linux distribution. And the "Windows NT" lineage is equivalent to the RedHat or Suse lineage for instance.
(One of the similarities of these "lineages" is that there usually is a major revision of the kernel between Windows releases, and that's also the case for a lot of Linux distros.)
Best Answer
Kernel versioning is independent of distro versioning, except to the extent that distros include patches of their own. This is indicated by tacking an extra identifier onto the version, e.g.:
Here
3.16.6is the version of the vanilla (unmodified) kernel, and-203is appended by the distro to indicate the relative version of their modifications to it.It's not necessary for you to understand that in any depth, just that the Linux kernel is an independent entity. Distros combine it with userland software and (in most cases) everything is precompiled to work together on a specific computer architecture (the most common one today being X86-64; some distros call this AMD64 -- they refer to exactly the same thing).
Most of the fundamental userland software actually comes from GNU, an organization distinct from that of the Linux kernel, hence the proper generic name for the OS is usually considered to be "GNU/Linux".
Software is bundled together in repositories managed by the distribution. When you install software, it comes from a default repository (e.g. "stable"), but you may configure the system to use a different one (e.g. "testing") to access different versions of individual things by default. You might also be able to specify a version and if it is not in the default repository, the installer will check a list of others for it.
Distributions come in two different sorts with regard to versioning themselves. While individual software is always being updated, most distros are also upgraded as a whole occasionally, e.g., from Ubuntu 12.x to Ubuntu 13.x. This enables them to make sweeping changes that might be too difficult to do otherwise. However, some distros instead use a rolling release model where there are not distinct releases, there is just one continuously updated version.
To summarize, the concept of versioning might apply to:
An example of a full package version string, which combines several of these things:
This is for a Fedora .rpm but other distros use similar schemes.
Foobaris the package name,4.11.3is the version of the source used,-4indicates the version of the patches applied by Fedora,f20is the distro version for which this package was compiled, andx86_64is the architecture for which it was compiled.