What is the difference between a rectangular coordinate system and a polar coordinate system?

rectangular coordinate system uses horizontal and vertical position to describe the location of a point. on the other hand uses Radius and angle to describe the location of a point.

the image on the right is the rectangular coordinate system. which uses x and y convention. while on the left is the polar coordinate which uses the r as the distance of a point from the origin and ##theta## as the angle of the radius from the horizontal.