In addition to different B cells reacting to different epitopes on the same antigen, B cells belonging to different clones may also be able to react to the same epitope.  An epitope that can be attacked by many different B cells is said to be highly immunogenic.  In these cases, the binding affinities for respective epitope-paratope pairs vary, with some B cell clones producing antibodies that bind strongly to the epitope, and others producing antibodies that bind weakly.