Use this to define the size of the sphere.
Defines the degree of the subdivision of the sphere. The sphere is divided along its latitude and longitude. However, like any other parametric object, until you convert a sphere into a polygon object with Make Editable, a sphere is always generated by calculation, no matter by how much you subdivide it.
With this drop-down list you choose of which surfaces, and in which arrangement, a sphere is to be composed. With Standard the sphere surface is made up of triangles and quadrangles, Hexahedron uses only quadrangles and Icosahedron only triangles, whereas Hemisphere will create a standard hemisphere, open at the bottom.
If you enable this option, a perfect sphere is generated by the math (if the sphere was not already distorted or deformed).
This type of sphere has the advantage that it looks truly round and smooth. In addition, it renders faster than a polygon sphere.