I have to do special things to remember them.
For "different" I say the word as diff-er-ent in my head every time that I say it out loud so that I remember.
For reference I think of a spots ref standing in front of a french flag, so I add the ref then I add the France and then I mentally add the "er" to "France" to get refrence, then after that " have to mentally go ad add the "r" and I finally come to "reference"
-starflower