The Spherical projection is for environment textures and IESAn IES light is the lighting information representing the real-world lighting values for specific light fixtures. For more information, visit http://www.ies.org/lighting/. light distributions. It performs latitude-longitude mapping for the U and V coordinates. For procedural textures, the W coordinate is the distance from the origin. Figure 1 shows the result of a Texture applied to a sphere using Spherical mapping.
Figure 1: A Texture is mapped to a sphere using Spherical projection
When using an Image texture to light a scene with the Sun And Sky node, Spherical mapping combined with a Transform node allows Texture rotation and translation on the Environment sphere.