I see that those circles look like a Venn diagram. But for a Venn diagram to be useful in explaining something, there needs to be an easily understandable defin

I see that those circles look like a Venn diagram. But for a Venn diagram to be useful in explaining something, there needs to be an easily understandable definition about what the 2 circles are. That doesn't seem to exist here. I can't come up with a logical definition for what the top circle or the bottom circle represent.