Wireframe - Models are built. Basic motion is blocked out. Camera angles are set. If there is a voiceover or script, it will be used as a template to time shots.
Simple shading - Basic shading and corrections from the first round are applied. This is the moment to assess how well information is being conveyed to a first time viewer.
Full render - Final materials and lighting are set. Text and other post effects are applied. The final product will be converted to any format(s) requested.