In WBJEE Counselling, there is no such provision that you have to choose the same branch changing the college only. The choices you fill in WBJEE counselling, would be based on your choice. If you choose CSE in ABC college, then you can choose CSE PQR College or can choose ECE or any other branch in ABC College. Let me give an example, you'll understand it better. So lets think, you have selected Computer Science and Engineering in suppose Institute of Engineering and Management as your first option. Then your second choice can be, CSE in any other college suppose Techno India Salt Lake or can be Electronics or any other branch in IEM.  During choice filing, you must put top colleges in the top of the list followed by average engineering colleges. You can also go through this link http://engineering.careers360.com/articles/wbjee-counselling

Hello,
WBJEE counselling is conducted to get admission to engineering courses in various colleges of West Bengal. Candidates qualifying WBJEE or JEE Main can participate in this counselling.You need to register online for the counselling, pay the counselling fee and fill the choices of your college and branch you are interested in the order of your preference. You need to lock the choices once you have filled it. After that the seat allotment takes place, depending on your rank, college &branch preferences and seat availability you will be allotted a seat. If you are satisfied with the seat you can join in the college by paying the provisional admission fee and reporting at the report centers with required documents for document verification and complete your admission process. There are three rounds of counselling you can participate until you get desired seat.
For detailed information you can check our article
https://engineering.careers360.com/articles/wbjee-counselling/amp

hi aspirant ,

yes defence quota is in wbjee counselling.

PLease check this link - https://engineering.careers360.com/articles/wbjee