Dressage training by Gareth Hughes - How to do the canter half pass 

@Pentonville Lodge Pups In leg yield the horse does not bend, it is straight, but it has slight flexion ( at the poll) away from the direction it is traveling. So in a leg yield to the right the body is straight but there can be a little flexion left. In half pass, the horse is flexed and bent ( around the inside leg) towards the direction they are traveling. So say in half pass to the right, the body is flexed and bent to the right, around the right leg.