This page exists within the Old ArtZone Wiki section of this site. Read the information presented on the linked page to better understand the significance of this fact.
There are three Shader Types available when creating a new shader: Material, Camera, and Light, and each one has a specific use.
In addition, each type can have different root bricks to form the base of the shader. Some root bricks cannot be added to some of the material types and if you try to add it, you'll get a stop cursor to indicate that this is not possible.