I recall reading an interview with R’ Herschel Shachter many years ago, where he said there were 3 principled differences between Modern Orthodoxy and the rest of the Yeshiva World. Paraphrasing, they were:
1) Whether secular learning is a value in and of itself (not just to earn a living);
2) Whether there is such a thing, or whether one must listen to, Daas Torah; and
3) Whether the State of Israel is Reishis Smichas Geuloseinu (aka Zionism).