Hi. I am not clear with what are you asking about in the question. But as far as I understand, you are asking about which bodies conduct JOSAA and CSAB. JOSAA was created by MHRD whereas CSAB was created by the CBSE. CSAB is responsible for filling up the vacancies left in nits/iiits/gftis after the JOSAA normally allot seats through its counseling. CSAB considers your AIR(All India Rank) whereas JOSAA considers your category rank.

Regards.