What is the difference between these hole shapes?
These are 3 different versions one the same shape / function that fit over axle.


The right one is the oldest from the 80
The left one came next
The middle one came after that.
To make it more confusing, lego is now back producing the right shape again


What I can remember had the original one a lot of clutch power and was hard to be removed. 

Personal I think the left one had some problems with manufacturing, due to the small tabs.

I believe the middle one broke easily.