From Consumerium development wiki R&D Wiki

    A mirror is an online service that includes, or "mirrors" or "reflects", substantially all of the content of another service, using it as a basis for its own ads or improvements: Nationmaster is a good example of a mirror of Wikipedia, though it is not a full GFDL corpus access provider.

    Wikinfo is not a mirror, strictly, though large portions of its content are mirrored from English Wikipedia.

    A reflector, by contrast, adds no substantial content of its own, and is simply another access point to exactly the same content.