The poll offered multiple choices to respondents who indicated they are Orthodox. They included Yeshivish, Hasidic, and Hareidi, all of which was categorized under Ultra-Orthodox. The MO category also had some other descriptors that fell under it.
Another interesting data point from the recent Avi Chai study shows that the number of schoolchildren in Modern Orthodox schools in the United States actually fell in the five year period from the previous Avi Chai study.