Well if you look at it that way, all Linuxes and Unixes are the same.
Did you get into system adminning at all, or did you just look at Gnome?
Different distros do some things differently, but yes, some things are the same. Distros have different philosophies, tools, paid/community support, reputation, people backing them, resources, purposes, etc.
But sure, basically, they're all the same.