Color | This node sets the object color without any lighting influence. This results in a flat, light independent shading. |
The Color Node is a specific preset of the Material Node using a NoLight Lighting Model. By changing the LightingModel Property Group to e.g. a Phong Lighting Model you can change your Color Node to a Material Node and vice versa.
A Color node is usually used instead of a Material node if any form of lighting or shading is undesirable for an object. It creates a flat shading that is unaffected by the light sources used in a scene. In all respects, it behaves exactly as a Material node, and has the same properties and controls.
Lastly, you can add Material Stages to the Node, for example to add Textures. Note that any channels which are dependent on lighting are ignored in the NoLight Lighting Model (Gloss, Specular etc.). For an in depth description of the Material Stages see the Material Node page.