I appreciate the observations... but I think a lot of the comments are just based on surface components.
For example, she can change back and forth between these 2 swings instantly just by modifying her starting stance. (narrow & open vs. wider).
I noticed when she starts narrow the swing is more up and more in line with a baseball pitch plane...and when she starts wider her swing is somewhat flatter and more in line with a softball pitch plane. Also starting narrow makes her swing more athletic and provides more power. Starting wider provides more consistency in squaring up pitches.
So really that fact that she can change instantly back in forth really means the underlying mechanics are the same....
batdragon,
In watching the gif, I notice that during her stride her rear leg straightens some and she seems to raise her body (her head also moves with this). Watch the horizontal slat on the fence behind her. Is this by design? If so, what benefit do you feel it creates?