Set E is constituent logic: the missing figure is made from the parts of the other two cells in its row. What is in both stays, or what is in either stays, or what is in exactly one stays, or one is taken from the other. Sometimes the parts stay separate and visible; sometimes they are superimposed into a new figure that has to be taken apart first.
What you see: two cells that look like parts, and a third that looks like their result. What you do: name the operation, then build the missing cell.