A parallelogram is known to be a two-dimensional structure. It comes with four sides. The sides of the parallelogram are obviously parallel with each other. A quadrilateral is also another two-dimensional structure. Unlike the parallelogram that will only have two sides, this will come with four sides. There are a lot of items in this world right now that are considered to be parallelograms.
You can simply look at your laptop, and you will already know that this is a parallelogram. A quadrilateral can be as simple as a rectangular table that you may have at home. Sometimes, quadrilaterals will have some sides that are not parallel to each other as compared to parallelograms wherein the sides are always compatible and parallel.