Hi,

JOSAA Counselling serves as the first step to the admission to IITs, NITs and IIITs, and they are based only on your category ranks. In case you belong to the OPEN category the AIR or ALL INDIA RANK is taken into consideration. But in CSAB, only the AIR is taken into consideration irrespective of your category.

Hope it helps.

CSAB is a special round or you can say that it is a spot round conducted when jossa councelling gets over.

In jossa councelling admission will be based on category rank but in CSAB councelling admission will be done by all india rank. CSAB councelling in conducted for all the  seats which is not fill in jossa councelling.