ProMotion is a technology that Apple debuted on the new 10.5-inch iPad Pro. It delivers refresh rates of up to 120Hz for fluid scrolling, greater responsiveness and smoother motion content. It also improves display quality and reduces power consumption by automatically adjusting the display refresh rate to match the movement of the content.
If you use the Apple Pencil, ProMotion results in just 20ms of latency for more fluid and natural drawing.
Take a look at the video below. You'll notice the scrolling of the 9.7-inch iPad Pro is clearly not as smooth as the 10.5-inch's.