What is the difference between jee mains and jee advanced?

JEE Main is the first exam. You must pass it to write JEE Advanced. Main is for admission in NITs and IIITs. Advanced is only for getting into IITs. Main is easier. The questions are more direct. Advanced is very tough. It has very difficult questions that check your deep concepts. Only top rank students from Main can give the Advanced exam. So it is much harder to crack.