tif vs. tiff

I am running Windows XP Home SP2. I also am running MS Office 2003 SP1
(have not put the SP2 patch on).

Thanks to Hal, the MVP, I got my fax console working again so that I could
see the faxes. I did this by changing my file associations so that tif
files would be opened by "Microsoft Office Document Imaging." I would like
to associate faxes, which I thought were "tiff" files with this programs
but associate "tif" files which I have for a lot of photos, with another
graphics viewer. However, it seems all my incoming faxes are "tif" and not
"tiff"

Aren't incoming faxes "tiff" ? If they aren't, could I set my fax program
to convert them to "tiff" as they are being received or is there some other
way I could set the associations such that a fax tif and a photo tif could
be opened by different programs?

Thanks.

Chet