The door edge guard is a add-on to protect the vertical edge of the door against dings and deformation when the door is opened. A body side molding is the horizontal part on the door that is installed by the car manufacturer, as protection against dings on the side of the door by other car doors opening into door and errant shopping carts, etc. Please see the illustration to the right for an example.
You are right! I was really wondering about this and I am glad that you’ve cleared that out. There are many different things regarding doors. I have a friend who does woodworking for a living and he has told me that people think a door it’s a door and that’s it, but that’s not the case. For example, the door has door frames like the ones from mdfskirtingworld.co.uk and much other stuff. And don’t even get me started about materials. You can make doors almost out of anything. You got to use your imagination and you can create many great things!