curious

Welcome Stargazer!

The Ubuntu 9.04 release notes (available on release) will most likely offer the information you want. They often cover new features, user-visible changes, bug fixes and such things.

The release notes for the current beta are here: http://www.ubuntu.com/testing/jaunty/beta

Also, Distrowatch, Linux Questions and similar release/info sites tend to offer well explained release articles.

Hope this helps.
Steve Pearce

Ubuntu is upgraded regularly to the next version every 6 months (actually, the version number for example for intrepid, 8.10, means just that: released in October(=10) 2008(=8)).
The main changes are always newer versions of applications, and bug fixes, so it is always a good idea (and generally can't hurt) to upgrade to each next release, once it is published. It will also contain security fixes, but those are published even for released Ubuntu versions, as long as those versions are maintained (usually the three latest releases are maintained). You will receive all security fixes automatically via the UpdateManager.

Here is a constantly updated list of major changes: https://wiki.ubuntu.com/JauntyJackalope/TechnicalOverview
These changes include new versions of Gnome (2.26) (that's your Desktop interface/environment), X.org (1.6) (that's the underlying window management) , the linux kernel (2.6.28) (that's the core of any Linux system), ext4 file system support, and significantly improved boot time performance.

ok that does explain alot even without reading the link you sent. the other question i have is at whatever point i do upgrade will my files be safe or do i have to reinstall? or rather will the upgrade preserve my files so i dont have to go trhought the process of getting all of it put back in?

Anything not within system folders will stay untouched by any upgrade (also release upgrades). This includes /home, which is essentially where all your files are stored. Even configuration files of your environment (e.g., Desktop settings, browser history/bookmarks/settings, etc.) will be safe, since these are also stored in /home/yourusername. That is one of the beauties of a clean linux environment - system and user space are 100% separated.
Concerning the installed files and applications, and also local system configurations, the upgrade will take care of that, and only update them to newer versions. Aside from a few exceptions due to arising incompatibilities with older/newer versions and such, the upgrade will neither install nor remove new and old applications by itself.
However, you should always read the Release Notes provided with a new release upgrade, since it will list important changes and caveats that might affect you.

Here is a page with a wealth of information about everything Ubuntu. I think it might be an interesting starting point for you if you want to learn more about the world of the little penguin :o)
http://yaserxp.wordpress.com/2008/05/29/discover-the-best-ubuntu-resources-on-the-web/