The American swing carries the kettlebell in a full continuous overhead arc rather than to chest height, and it is double-arm. The longer range asks for more shoulder and upper-back mobility and projects the kettlebell further, which is the reason some lifters choose it.
The drive underneath can be any of the three: a hip hinge, a squat, or a pendulum. The overhead finish comes two ways. One is a shoulder raise, where the shoulders carry the bell through the last part of the range. The other is a press-out, where you keep the bell closer and press it to lockout, which is the more efficient of the two and the better choice for high reps.
Good shoulder flexibility, stability, and strength are required because both arms hold the same handle close together while overhead. When performing the shoulder raise version, controlling the deceleration matters — a movement that is not slowed in time has the potential to load the shoulders hard.
The exercise is safe when the prerequisites are met and the load is honest. The fault to watch for is cranking the head back or arching the low back to get the bell overhead instead of finishing with a neutral spine.