While most beaters in a mixer rotate in a circular motion the Kenwood bowl tools move in a 'planetary' way.
This means that while the beater is revolving in one direction, the socket turns in the opposite direction making sure all the mixture is picked up from around the side, bottom and centre of the bowl.
It ensures the mixture is combined together thoroughly and is consistent whether you are whisking one egg or 2.4 kilos of bread dough.