What is the difference between all of these Debian version numbers?

In attempting to find the version of Debian I am running, I have run several commands; the confusing thing is, nearly all of these commands return different results.

For instance, in /proc/version I find:

Linux version 3.2.0-4-686-pae (debian-kernel@lists.debian.org) (gcc version 4.6.3 (Debian 4.6.3-14) ) #1 SMP Debian 3.2.63-2+deb7u2

I can tell 3.2.0-4-686-pae is the kernel version, this is clear to me. But the rest of the output seems to give two different Debian version numbers of 4.6.3-14 and 3.2.63-2+deb7u2 (the latter also being output from uname).

Moreover, when I look in /etc/debian_version, it tells me I'm using version 7.7.

Why am I getting so many different Debian versions listed in these places, and what is the difference between the numbers?