There is a huge difference between the two if you want to get selected in iit for btech course then you will have to qualify jee advanced and get a valid rank and then sit in josaa counselling and then depending upon your choices and your rank you will be allotted an iit with a particular stream so by now you might have understood that to get an iit you need to qualify jee advanced but if you qualify jee advanced then that does not necessarily mean that you will get an iit