The difference between a circle and a sphere is that a circle is a plane figure, while a sphere is a solid.

1- circle is a geometric figure called circle;

Definition of a circle:

The set of points whose distance from a fixed point on the same plane is equal to a fixed length is called a circle. This fixed point is called the center of the circle.

Two-dimensional sphere

Definition: A semicircle rotates a Zhou Suocheng around a straight line corresponding to its diameter. The spatial geometry is called a sphere.

Sphere is a three-dimensional figure with a continuous surface, and the geometry surrounded by sphere is called sphere.

There is no absolute sphere in the world. Absolute spheres exist only in theory.

But in a weightless environment (such as space), the droplets will automatically form an absolute sphere.

As shown in the figure: