baronsmeg:
Adaptability affects the types of
attacks, while Conversion affects the types of
moves. A move's type can't change, while an attack's type can. For example, the move Hidden Power has the type Normal, while the use of Hidden Power, the attack, can have various types depending on the Pokemon.
My description for Conversion reads in part:
"User's types become the original type of one of the user's
moves, except this move, chosen at random."
Conversion would always treat Hidden Power as Normal.
My description for Adaptability reads:
"If an
attack by bearer shares a type with one of bearer's types, that attack's effectiveness is doubled instead of multiplied by 1.5."
Adaptability would not treat Hidden Power as Normal.