How many more sides does a nonagon have than a quadrilateral?

A nonagon has 9 sides, while a quadrilateral has 4 sides. Therefore, a nonagon has 5 more sides than a quadrilateral. The difference in the number of sides between a nonagon and a quadrilateral is calculated by subtracting the number of sides in the quadrilateral from the number of sides in the nonagon, which is 9 - 4 = 5.