First coming to second part of your question csab and csab neut are different csab is open for all students csab neut is for northeast and union territory students then coming to details of csab then csab is a counselling conducted by central seat allocation board which is done for allocation of leftover seat after josaa counselling in this there are two rounds and you have the option to withdraw after first round and after the second round the seat allocated to you is binding and you will not get any refund if you do not join that college you can also participate in csab after participating in josaa counselling as well and note that csab counselling is done only for nit iiit gfti colleges and more information can be found from the original website of csab which is csab.nic.in