People often interchange flip and cast and they are two different motions. Here are my definitions.
Cast-where the angle between left arm and the shaft is “thrown away” well before impact. The right wrist becomes bowed and the left wrist cuped. This is usually an action that is a result of a long back swing and not enough rotation to sustain the angle…or just plain grabbing it with the right hand and throwing the club at the ball. It can also happen when the upper body moves in front of the ball and all power is lost. Not unlike a baseball player being fooled on a breaking ball or change up and ending up on his front foot too soon. Hanging back on the right side can also “force” you to cast/throw the club at the ball just to get it there.
Flip-Usually the result of the club being under the plane or the face being too open just before impact (often both). In order for the face to “catch up” the turn of the body (pivot) stalls and the hands “flip” the club closed in order to avoid a blocked shot to the right. Often resulting in a snap hook.
As you can see, these are two completely different issues and whatever definition you choose to use…be advised that when discussing these issues, you and your cohort are discussing the same thing.