[plt-scheme] syntax-object comparison

I'm having trouble figuring out all the differences between the
syntax-object comparison procedures.  Can someone please give examples
where the following procedures will give different answers?

  bound-identifier=?
  free-identifier=?
  module-identifier=?
  module-transformer-identifier=?
  module-or-top-identifier=?           ;from (lib "stx.ss" "syntax")
  (lambda (s1 s2) (eq? (syntax-e s1) (syntax-e s2)))

An example of what exactly `syntax-local-get-shadower' does would be
great too.

Thanks,
--dougo at ccs.neu.edu