Usually whenever we think about gradschool we think about the switch from "doing classwork, quals, etc" to "dissertating" is a single-step process, which we call "becoming a PhD candidate" (as opposed to being a PhD student). In practice there are over half a dozen steps. Filing the paperwork declaring your completion of classwork, quals, etc is just the first few. (Okay, easy enough) Then there's the prospectus, for the graduate school. (The what for the who now?) Then the forming of your research committee. (Right, okay) Then the proposal. (Wait, how is this different from the other thing?) Then the proposal defense. (Um, okay, but not every department requires this?) Plus a few other steps I'm surely forgetting.
As of yesterday, I am officially finally totally completely absolutely done with all the paperwork, and can finally get back to actually working on the thesis itself!