What is the difference between a rhombus and a parallelogram?

Rhombus: a polygon with 4 congruent sides

Parallelogram: A polygon with 2 sets of opposite parallel sides, can have right angles

A parellelogram is a quadrilateral or four-sided figure in which the opposite sides are parallel. Also because the opposite sides are parallel, hence the opposite angles are also equal. A rhombus, on the other hand, may be defined as an equilateral parallelogram.