Document describing a design system, explaining its rules with concrete examples. Often employs a "Dos and Don'ts" schema.
Also: CI Guide
Living Styleguide
HTML version of a Styleguide.
Includes and documents live code examples alongside relevant rules.
Component Library
Technical implementation of all frontend components needed to create websites and applications that should feel and look alike. Often is a the result of a project also using a Living Styleguide.
patternplate
An OpenSource software to create Living Styleguides and Component Libraries efficiently. It provides a ready-made Web interface to display Living Styleguide contents alongside an automatic listing of component in the documented component library