PhD's do "dissertations". But it is a a "thesis" that you should be looking for, since it's only claimed BHO Sr. had a Master's degree, for which one must (generally) write a theis. I did, but my wife did not. Of course she was on the doctorate track, and they often are allowed to skip the thesis, but take more credit hours of classes. She later wrote a dissertation. Younger daughter is working on hers now.
Sorry for the misnomer. I have seen it put both ways. At Harvard, there is no Master’s thesis in the Arts and Science degree programs. The degree is usually given after completion of required courses and passing general exam.