Hello aspirant,

B Category seats means, seats which are filled on merit basis or JEE Mains rank, etc.

There will be A Category seats which will be filled through State Level  Entrance exam Counselling or National Level Entrance exam which depends on College you want to join.

Coming to B Category seats can be filled without counselling and fees is also a bit more in Some Colleges and B Category seats also includes Management quota seats or NRI quota seats. Some Engineering Colleges offers B Category seats on the basis of JEE Mains entrance exam marks.

I hope this information was helpful to you.

Best of Luck!!