Specifies one or more of the following keywords. Each keyword
    indicates a type of class difference to show.

    Keyword                   Difference Type

    GENERATION_DIFFERENCES    Directs CMS to show the difference if the
                              generation in one class differs from the
                              generation in the other class but one
                              generation isn't a variant of the other
                              generation.

    VARIANT_DIFFERENCES       Directs CMS to show the difference if the
                              generation in one class differs from the
                              generation in the other class and one
                              generation is a variant of the other. One
                              generation will be a variant of the other
                              if at some point in the path between one
                              generation and the other a generation is
                              reserved and replaced /VARIANT.

    If the /SHOW qualifier is not specified, both generation differences
    and variant differences are shown. If a generation of an element is
    in one class but no generation of the element is in the other class
    then the difference is always shown regardless of whether the /SHOW
    qualifier is specified or not.