[ The previous revision of this question didn't get much response and was incomplete because it did not include the derivatives, at least one of which also has editions. I have revised it to hopefully be more complete and I have switched it to a community wiki. ]
Note: If you have a suggested set of tags to identify the various Ubuntu editions and derivatives I would recommend posting them as answers so that they can be voted on and discussed.
#Current usage on Ubuntu.com
On the official Ubuntu website the term "edition" is used to indicate the various formulations of the main distribution.
In the past Ubuntu Netbook was also known as the "Netbook Remix" but Jorge Castro noted that this usage has been officially dropped in the latest releases.
The official website divides the known derivatives into several groups:
- Recognized (significant contributions to the overall project)
- Localised (support for languages not included in the main CD release)
- Other (see the derivatives wiki for more lists)
It seems reasonable to limit this discussion to the main Ubuntu distribution and the recognized derivatives. Based on the derivatives wiki an attempt to be more inclusive could easily become quite confusing. The recognized derivatives are:
- Kubuntu - Ubuntu with the K Desktop environment
- Xubuntu - Ubuntu with the XFCE desktop environment
- Ubuntu Studio - Designed for multimedia editing and creation
- Mythbuntu - Designed for creating a home theatre PC with MythTV
- Edubuntu - Ubuntu for education
According to the project website Kubuntu has two editions:
- Kubuntu Desktop (usually just "Kubuntu")
- Kubuntu Netbook (also known as "Kubuntu Netbook Remix")
The Edubuntu derivative doesn't appear to have editions in the same sense as it's siblings but that project does produce several "application bundles" including one that is intended for installation onto a Kubuntu-based system.
#Current usage on the Ubuntu Stack Exchange
Desktop Edition
The desktop edition appears to be mostly tagged as ubuntu-desktop. There were previously two questions tagged desktop-edition but I retagged them to the former tag because it was more common.
There are also a significant number of questions tagged desktop but it isn't clear how many (if any) of those are using the tag to mean the Desktop Edition.
Netbook Edition
There are quite a few tags that refer to the Netbook Edition. The most common tag appears to be netbook (but at least two of those questions refer to the netbook edition of the Kubuntu derivative). The second most common appears to be une.
It would appear that the unr tag is supposed to be remapped to ubuntu-netbook-remix as a synonym but it may not be working quite right at the time of writing this.
Server Edition
Questions about the Server Edition appear to be tagged with ubuntu-server. There were some questions tagged server-edition but I changed those to ubuntu-server because it was more common. There is also a server tag and many (or possibly all) of those questions are about the server edition as well.
Kubuntu Desktop
At the moment, Kubuntu Desktop questions are tagged with either kubuntu or kde (and both in a few instances).
Kubuntu Netbook
The Kubuntu Netbook Edition questions are tagged either with knr or double tagged with kubuntu and netbook. Most of the other questions tagged netbook are referring to the main distribution (as noted above).
Xubuntu
Questions relating to the XFCE-based derivative are tagged with either xubuntu or xfce.
Mythbuntu
Questions regarding the home theatre derivative are tagged with mythbuntu. However, there are also some questions tagged with mythtv which I have not reviewed to see if it could be considered a synonym for mythbuntu or if there are just specific to that particular application.
Edubuntu
There do not appear to be any Edubuntu specific tags at the present time.
Ubuntu Studio
There do not appear to be any Ubuntu Studio tags at the moment.