Another difference between a form, variety, etc. and a subspecies is that subspecies have official standing with the ICZN as a scientific name.  If a later study decides that a recognized subspecies is actually different enough to merit species recognition, the subspecies name becomes the species name.  Conversely, if a species is demoted, its name can become a subspecies name.  However, any variety, form, etc. proposed after the standardization of scientific naming (mid-1930's, if I remember correctly) has no official status.  Although it looks more impressive, Homo sapiens forma cinncinnatiensis has no more official status than Homo sapiens variety A or Homo sapiens "Art Weil".  Varieties, etc. published before the standardization count as subspecies.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa