Swing
Swing occurs when using a frame that maintains an associated line from the shoulders through the knees (as often used in ballroom dances). To create swing the dancer does a swinging action around their hips, moving the knees forward or backwards and the shoulders inherently move in the opposite direction to maintain the associated line. The dancer’s center is the most static part of this motion. Swing enables smooth parallel motion leads and body shaping.
Sway
Sway is a rotational shaping of the upper body and raise of the hip added to swing. Sway creates internal Counterbalance as a tool dancers can use to control Pillar of Momentum. It also changes how dancer’s bodies relate to each other in a closed frame, and can be used to create more space to step past each other or to change the frame.
Related Ideas Pillar of Frame Change of Frame Lead