<p>Your AB subscore is more than just the identical questions. For instance, one of the BC-only questions contains parts each year used for the AB subscore. The AB subscore simply means only those materials that could be on the AB exam, not necessarily questions that actually were on the AB exam.</p>
<p>Also, BC really only takes on another 20-25% of the material that AB covers. In that sense, it’s not really a year-long class that would follow AB. It either would be taken instead of AB, or it would be offered after AB with some additional non-AP materials as well.</p>