I am going to definitively distinguish between these two terms.
They are used interchangeably and wrongly in my opinion. They happen for different reasons…and they are both completely different than a club that releases gradually from the top, when the club face is connected to the turn and rotates with the turn.
When the turn is slightly out of sync, the natural rolling of the wrists can cause off line shots, but it is neither a cast or a flip. It is natural rotation of the hands, forearms and club face, that didn’t quite link up with the turn for whatever reason.
Bad golf shot…big deal.
A cast is when both wrists break down. For a right hander, both wrists get severe angles in them before impact and the hands will be behind the ball at impact. The often cause is either getting the spine in front of the ball before impact or a back swing that is too long and the individual cannot create enough rotation or speed to deliver the club to the ball properly. It can often both of these.
A flip happens when the club is either open, or under the plane coming into impact…usually both. The hips have to stall to allow the club to catch up and the wrists roll right before impact.
A flip is actually close to the right move, it just happened way to late.
An early release is what happens when a proper release is forced too much, independent of the turn (pivot). People who learn that holding the lag is bad and try to retrain their body to make the natural move will do this. They will roll their wrists is the proper manner, without it being connected to the turn and everyone tells them it’s a flip…and it is not. It is just a mistimed proper golf swing that needs to link up.
A flip is what happens when the release is delayed too long. In order to keep the ball from going way right the hands flip the face closed at the last millisecond before impact. Holding the lag and swinging too far from the inside will cause this.
Lots of technobabble, but I think these explanations will help some people trying to learn to release it properly.
Remember, release means let go, not force something.
I am sure there are questions in need of clarification, so fire away.