what is the difference between online MBA and distance MBA according to the exam question pattern and can I attend the exam from anywhre

The only difference is between distance & Online MBA   that distance programs have real classrooms, whereas online programs have a virtual classroom. There is no any big difference in exam pattern, the level of the questions are same for both. And you can give the exam from any place for Online MBA & Distance MBA.

An online MBA programs curriculum usually consist of lectures, reading materials, and assignments available for download as electronic form as text, multimedia and audio files.
Whereas Distance education refers to course study where the educational institution is not located in the same city as the students. The study materials are handed over to the students in form of videos, notes and online programs etc.

I would suggest you that Online MBA is best because its quality, status, and popularity continues to rise.