A circle is a figure, and a two-dimensional sphere is a three-dimensional object. One can only calculate the surface of a circle, whereas it is possible to calculate the volume of a sphere. A circle is a basic closed curve, which divides the plane into two regions.

Asphere is a round, solid character by its surface, and every point on its surface is away from the center. A circle is a shape with all positions at the surface, equal distance from the sphere. Some common examples of a circle include bangles and tires. Common examples of a sphere include tennis balls and planets. A sphere has a larger volume but a smaller surface area.