Not exactly. The Distros can make lots of changes. Ubuntu officially supports Gnome, but has a bunch of preinstalled extensions and settings tweaks that change the look and feel.
If you want to know the “official” look of Gnome, as I said, check out Fedora. By default, I’m pretty sure the only enabled plugin puts the Fedora name in the bottom right corner.
In fact, if you want to know what the most plain, standard setup for any major DE is, check Fedora’s spin: Fedora KDE, XFCE, LXDE, and so on all start very vanilla on Fedora.