The basic difference is that once JoSAA completes its process of admissions for IITs, NITs and other colleges, CSAB conducts some special rounds(generally 2 rounds) to fill up the vacant seats of NITs, IIITs and other colleges (not for IITs). 

Eligibility for CSAB special rounds:

1. All the candidates who are eligible for JoSAA counselling are equally eligible for CSAB. 

2. If you are not allotted any seat via JoSAA then you can switch for CSAB. 

3. Even if you are holding a seat, then also you can apply for CSAB special rounds. (There might be chances to secure better branch). 

Hope this will help you. 

Hello Sandeep!

JoSAA is a common portal for admission to NITs, IIITs, IITs, Government Funded Technical Institutes, etc. Single application and choice list has to be submitted for admission to any of this.

Till 2014, we had CSAB that was for admission to NITs, IIITs, etc. and there was separate portal for admission to IITs. Since 2015, both of them have been merged to make the entire process more easier and simpler.

Yes,one is supposed to apply on both the platforms but firstly we should know that Josaa counselling and csab counselling is not held parallely. After completion of all round of Josaa counselling csab conduct spot round counselling on remaining seat for Nit , Iiit and gfti. If you are already participated in Josaa counselling and didn't get a seat, you can definitely register for csab also.

All the best for your future :)

Thank you :)