Theory:

\(3D\) shapes are three-dimensional solid objects. The three dimensions are length, breadth, and height.
 
While \(2D\) shapes are flat, the objects of \(3D\) shapes have the depth to them.
Example:
we consider sphere to be a soccer ball in \(3D\) shape. While circled on a piece of paper and known as circle's \(2D\) shape.
2d-and-3d.gif
 
More 3D shapes.
output-onlinepngtools (14) (2).png