title_body: Why is the noise in my accelerometer more pronounced than the noise in my gyro?
upvoted_answer: A large change in acceleration doesn't necessarily mean a big change in velocity. Since the chance in velocity is the integral of the acceleration, the velocity will barely change if the acceleration spikes quickly for example.
  Something that I don't quite understand is why the two graphs doesn't match. By definition, the acceleration should be negative when the velocity decreases, and positive when it increases. It doesn't look like that is the case here, even if the zero value on the y-axis is wrong. So it is possible that One of the sensors gives you the wrong readout.