What's the difference?

Looking at a regular 'M' that has the wide pickup, net wrap, twine tie.

My fleet of aging "J" are a mix of super and non-super varieties.. I know the differences in them.  

Other than the  'super J'  having  one  roller  that is  hung with larger bearings,    the rest of the  stuff  was  kinda  an option  thing;   auto steer,  auto oiling,  double  arm tie,  bale kicker..  etc.

Same  differences  in the  "M"?