B Category seats are nothing but Management Quota seats of Private Colleges. Even they are filled on the basis of reservation. Like OBC has 27%, SC has 15%, ST has 7.5% and EWS has 10%. This reservation is only applicable if you are applying for the seats of Private Colleges of your State. But if you want to apply for Management Quota seats of other State Colleges, then you lose out on the reservation. Then you will be considered as a General Category student no matter what Category you belong to or how  much reservation you have.