What is the difference between a 2013 and a 2014 ICB playlist?

Note that ICB playlists marked as '2013 Playlists' refer to assessments written between 1 April 2013 and 31 March 2014; while ICB playlists marked as '2014 Playlists' refer to assessments written between 1 April 2014 and 31 March 2015.