This area of the rules is really complicated, but let me show you two classic interference situations to help explain the difference between a let and a stroke.
In the first one, one player is denied access to the ball. The opponent is trying to get out of the way, and the next player to play or "the striker", can't get round her opponent.
This is a let ball, and the rally is replayed.
As a rule of thumb, if someone is trying to get to the ball and can't get there because of their opponent is in their path, it results in a let.
In this second situation, the striker can't play the ball, as her opponent is in the way. The difference here is that she is ready to play the shot only she can't swing because she would hit her opponent.
This is a "stroke", and the striker is awarded the rally.
The rule of thumb here is that the striker is at the ball, and still can't play a shot.
It's important to note that this is a really simple way of looking at lets and strokes, but it holds true in most of the situations you'll find yourself.
In this example Laura has hit the ball very wide and Natalie follows the ball as it travels around the back corner. As she has allowed it to pass around her she is deemed to have "TURNED" and she asks for a let in case she hits Laura with the ball.
The rules award the rally to the opponent if you strike them with the ball after the you have 'Turned'. This is designed to make the game safer as when 'Turning' occurs you are generally unsure of your opponent's position and are in effect playing blind! So if after you have 'Turned' you are worried you will hit your opponent, STOP and ask for a let. It will normally be granted and the point is just not worth the blood, sweat and tears!
