Comment 10 for bug 151492

The debdiffs are needed for the security updates, where Ubuntu keeps the same version and backports fixes.

Packaging a new upstream requires more work, and while a debdiff (or in this case interdiff) is needed, the full debianized source package will also need to be provided. Here a couple of places to get more information:

http://doc.ubuntu.com/ubuntu/packagingguide/C/index.html
https://wiki.ubuntu.com/PackagingGuide/Basic#NewPackages

I also can't recommend enough going to #ubuntu-motu on Freenode IRC. They are great people and you should be able to get real-time help from the community. If you are unfamiliar with IRC, see https://help.ubuntu.com/community/InternetRelayChat