Don't understand how Ring Doorbell 2's motion zones work

I have a Ring Doorbell 2, but I really don't understand how the motion zones work. In the app, in the setting of the motion zones, you can see 2 different zones: (please see the attached picture on the right side) A: a running man icon with the lighter blue area. I think-this is for general detections that you usually care about. B: a car icon with the darker blue area. It seems to me that this is for detecting the traffic. That means you don't want to be notified if motion detected. Is my understanding above correct? My problem is that when traffic passes through zone B, I receive motion detection alerts. This is not what I want because I don't care about the traffic on the road. So what's different between Zone A and B? and how to deal with the unwanted traffic notification? Should I tweak the coverage range, making Zone B don't cover the road? PS. I have installed wedge