If you say something is indisputable, you’d better be pretty sure about it. Indisputable is used to describe something that is so obviously true that there is no room for questions or debate.
If you dispute something, you question it, such as disputing your friend's claim that he is the faster runner. You might have a race to determine who's right. But if something is indisputable, it is beyond question or doubt, like if your friend also happens to be an Olympic marathoner and you can barely jog a mile. But pay attention — if someone is calling something indisputable that's really a matter of opinion or taste, it's debatable. Indisputable requires facts.