Difference between vim-gtk and vim-gnome
Both packages provide the same application, but compiled with different dependencies (e.g. vim-gnome depends on libgnome2). Vim-gtk is important only to people who use Kubuntu (or some lightweight desktop environment) and don't want to install GNOME libraries. If you use the standard Ubuntu desktop, the dependencies are already present, and you can safely use vim-gnome. I agree that it could be confusing.