The name RenderMan can cause confusion because it is often used to refer to different things developed by Pixar:

• The RenderMan Interface Specification (RISpec), Pixar's technical specification for a standard communications protocol (or interface) between 3D computer graphics programs and rendering programs.
• RenderMan Shading Language
• PhotoRealistic RenderMan (PRMan) A RenderMan Interface Specification-compliant rendering software system developed by Pixar based on their own interface specification.

3D graphics software | Pixar

RenderMan | RenderMan | RenderMan | RenderMan | RenderMan | RenderMan