The Shell material is for use with . When you use Render To Texture to bake a texture, it creates a Shell material that contains two materials: the original material used in the rendering, and the baked material. The baked material is a bitmap that is saved to disk by Render To Texture. It is “baked,” or attached to an object in the scene.
The DirectX Shader material enables you to shade objects in viewports using DirectX (Direct3D) shaders. With DirectX shading, materials in a viewport more accurately represent how the material will appear in another application, or on other hardware such as a game engine. You can use this material only when you are using the and DirectX 9.0 or DirectX 10.0 is chosen as the Direct3D version.