If you drift between distributions, one of the first things you might notice is that Gedit, GNOME's text editor, is not always the same on each system. For instance, in Debian, Gedit is a relatively simple text edit, while in Ubuntu, it sprouts features that Debian users may never have seen. The difference is the plugins that each distribution packages with Gedit and enables by default. Many of these plugins make only small alterations by themselves, but enable a dozen or more and you'll find Gedit transformed almost out of recognition, regardless of whether you are using it to write code or plain text.
Some Gedit plugins come standard in Gedit, although your distribution may not enable them by default. Others are available in the Gedit-Plugins package carried by many distributions. Still others are unofficial and available separately, and you must add them to the ~/.gnome2/gedit/plugins directory in your home directory.