* Distribution (Mandriva / Mageia / Fedora / ...)
  * releases (Mandriva 2010.0 / Mandriva 2010.1 / Mandriva cooker / Mageia cauldron / Fedora rawhide / Fedora 13 / ...)
   * media (main / core / extra / non-free / ..., + plf / mib / write_your_third_party_media_here ? )
    * arch
     * rpm


 * package (eg. : virtualbox)
  * rpm (eg. : virtualbox-3.1.8-3mdv2010.1.src.rpm)

Package concept is independant from distribution / releases / media, etc. You go from packages to these notions by the rpms attached to that package.