Venn diagrams are great. They can quickly show the relationships between multiple conditions or sets (as they are called by mathematicians). Most of the time, they are drawn using circles. This is fine, but there are some advantages to using rectangles. For example, it is easier to group multiple rectangles than it is to group more than 3 or 4 circles. Or, if it is desired that both the size of the rectangles and the size of the intersection are to scale, it is easier to do that with rectangles. Beyond that, rectangles can look different if you are used to looking at circles.
Below is a rectangular Venn diagram showing the relationship between what an employee wants to do, what an employee is actually doing and what the company needs. I could describe it, but, the beauty of Venn diagrams is that they are very easy to understand.