What is a square a parallelogram but a parallelogram not a square

A parallelogram is considered a more general heading therefor a square would fall under it as well as rectangles rhombi and trapezoids. squares have the exact same properties as parallelograms.

The sides of a square are parallel and all the angles equal 360 degrees, so it's a parallelogram. A parallelogram is not a square because a squares angles need to be 90 degrees.