The difference is that the CE is like a testing version, whereas the Official one is when they are satisfied that as many bug's as is practical, have been ironed out.
In theory, a fully updated CE, should be as complete as the Official one.
Your Q's about updating the distro though. The ones that I'm aware of that offer facilities like this, would be like debian and gentoo (there are probably others, but I haven't looked into them).
The downside, is that because they are "power distro's", they seem to favour doing a lot of the setup/config manually. This seems to mean that you need a fair bit of prior knowledge.
The mega advantage is that with debian, you can open a terminal, and as root issue a command like
or something like that, and it will download/install the very latest version available. You'd need to follow their descriptions of the differing versions, because to the novice, debian's stable/unstable/testing terms can seem a little un-nerving. It's not as scary as it might seem to the uninitiated. There's a bit more too it, but that's basically it.
Gentoo is similar (though in my opinion, is a little easier to install/setup). It can take a little longer to install, because it's based on source, as opposed to pre-compiled binaries (deb's for debian, rpm's for mandrake, fedora/redhat, SuSE, etc etc). But again you can just upgrade it with a single command in a terminal
again, there's a little more to it, but basically bingo, you've got the latest (actually I prefered gentoo, because I felt that the install instructions/guide was considerably easier to follow for a nugget like me!).
That said, I also maintain mandrake, because that's the first distro I managed to get on with, but gentoo is easier to manage.