Acceleration speed is the control for the extra speed that's added to your aim camera when you are using high amounts of stick deflection.
Ramp Power Scale is a bit more complex, it controls the curve between aim camera movement and stick deflection. At 0, the curve is linear, meaning at 20% stick deflection your camera will be moving at 20% of the max sensitivity. The higher the number, the more that curve deepens, meaning you'll get less sensitivity at lower deflection but a bit more as you approach the top end. The max movement won't change though, that's controlled by Sensitivity and Acceleration.