For any atom there is just one 4s orbital. The image on the left is deceptively simple as the interesting features are buried within the orbital. That on the right is sliced in half to show that there are three spherical nodes in the 4s orbital.
The origin of the spherical nodes becomes clearer upon examining the wave equation for this orbital.
While still spherical, the higher s-orbitals (5s, 6s, and 7s) are more complex still since they have more spherical nodes.