What is the difference between the motion detection of the old camera and the motion detection of the new smart camera?

The old camera had a frame that triggered the recording. The new camera captures every movement in the frame. So it is not necessary to step through the frame - if someone appears in this frame the recording is triggered. The zones must neither touch nor overlay of each other.
With high sensitivity, even a shadow triggers the recording. With lower sensitivity only an animal or human triggers the recording.