Differences training-although called "training"-is a formal flight that is conducted as a single training flight by an authorized personnel, and must be documented....you may not call it a check-but thats basically what it is...you can call it training as well, does not matter..its a flight that has to be done before you can fly the differnet variant...
Like is said above-not sure why you are trying to make a fuzz about it-i clearly stated that one needs two type ratings (bascially four-as each type rating can be single pilot and multi pilot, and dont forget the IR which is a different rating as well)...