... it has a slightly different technique that involves breaking
the wrist when releasing the ball ...
This is termed "Loading and
Unloading".
Loosely, loading means that prior to entering the leverage position
at the bottom of the swing, the bowler cups their wrist to position
their hand under the ball.
The unloading action is executed during and throughout the entire
release. From a fully (or partially, depending on how much hook is
required) cupped position, the wrist flattens to a straight
position and proceeds smoothly to a broken position. This entire
action is very quick in real-time.
... which uses gravity to increase the RPM instead of the
traditional lifting of fingers ...
I'm not sure about gravity effects, but unloading at any time
during a release is generally a method to increase the amount of
leverage one can get onto the ball.
----------------------
This method defies the widely-held notion that "broken wrists =
weak release; cupped wrist = big hook" that many regular bowlers
have. While that may be true, the action of unloading mid-release
imparts more action to the
ball; similar to the way an animal trainer cracks a whip (after
whippping, the arm always returns like a recoiling motion).
If you can't picture this, don't worry - its normal. The loading
and unloading method is very difficult to understand and harder to
learn, let alone master. That is why its generally acknowledged as
an advanced technique.
For those who wish, try to get your hands on some video clips of
the PBA bowler Chris Barnes. He's widely known as the most famous /
accomplished practitioner of this technique in the professional
leagues. He uses this method on ALL his first shots, and breaks his
wrist all the way for spare or fuller shots.
In Singapore, Shaun Ng is the best in the business, in my opinion.
If he's still bowling, you can watch him. 
