What is the difference between IIT, NIT, IIIT and DU? Which is a better institute in all the aspects?

For different institutes, there are different exams. For IIT, you have to pass JEE Advanced. For NIT, IIIT or GFTI, you have to pass JEE Mains. These Institutes will give you the degree of B.Tech and DU is a university which is for B.Sc or M.Sc.