While shading nodes control the appearance, these settings control the quality and algorithms that each renderer uses to render the material.
These settings control the 3D Viewport display in solid shading. They provide a faster alternative to full shader nodes, which may be too heavy or distracting for tasks like modeling, layout or sculpting.
Diffuse or metal surface color.
Blends between a non-metallic and metallic material model. A value of 1.0 gives a fully specular reflection tinted with the base color, without diffuse reflection or transmission. At 0.0 the material consists of a diffuse or transmissive base layer, with a specular reflection layer on top.
Specifies microfacet roughness of the surface for metal and specular reflection.