• Incorrect sir/madam! I’ll start by thanking you for making me look this up and question my own assumption about the world. In fact, a venn diagram is any diagram that shows all possibilities in a set where a euler diagram shows only relevant relationships. So, for this example, the venn diagram would be 2 circles with no overlap because there is no relationship, but all members of the aet must be represented. The Euler diagram of the same could, arguably, be null or blank as there is no relevant relationship to display. Though, I imagine it’s also correct enough to use the terms interchangeably in a diagram where the relevant relationship is an empty set.

    • “shows all possibilities in a set”

      fwiw, I’m only jokingly being a pedant, but a Venn shows all relationships not all possibilities — therefore a diagram with no relationships would not be a Venn.