What is the difference between E-type system and Doriot system?

The E-type system is a design of coupling between current handpieces. It was studied and standardized by ISO-3964 and allows the use of several different brands of contra angle and straight handpieces in micromotors, so the handpieces engage without damaging and decreasing performance.

 The Doriot system was a systematic coupling where the oldest micromotor has already itself a straight handpiece, providing that only one contra angle was coupled in it.