What is the difference between these two types of drill? I have always bought SDS+ for my ELU machine and was always under the impression that there was a difference in the tool holders and the drills were not interchangeable.. However having mistakenly picked up an SDS max drill bit and thinking I may have to return it, I compared it to all my other bits and then noticed there was no difference. Went on to use it and it performed as normal.

Richard