In Venn diagrams, all areas (subsets) are shown. Areas that contain no elements (empty subsets) are filled with black color.
In Euler diagrams, only areas that contain elements (non-empty subsets) are shown.
If we want to depict all areas, irrespectively of whether they contain elements or not, We should choose to make a Venn diagram.
If we want to avoid depicting areas that contain no elements, and instead focus only on the areas that are non-empty, we should choose to make an Euler diagram.