There is a main difference between Basel II and Basel III. In Basel III, there is a 4.5% capital buffer to absorb shock. With Basel II, there is no capital buffer.

Basel I dealt with Capital Requirements for Banks.

Basel II deal with Capital Requirements for Banks, Supervisor Review and Regulations, Market Displine.

Basel III is same as Basel II with the enhancement of having Capital Buffer upto 4.5% which is not a part of Basel II.

in basel II there is no capital buffer but in basel III buffer is 4.5 % to be achieved upto jan 16 to absorb the shock

Basel II is the second set of recommendations released by Basel Committee on Banking Supervision. These recommendations are directed towards international governments for the purpose of creating a standardized international banking system.

one is 2 and the other is 3