tiff to xls conversion can actually mean many things, the most obvious one being inserting TIFF picture inside Excel spreadsheet as object.
However TIFF files are quiet often also used for maps / GIS files so this might also be used for export of metadata from the files and store them in separate, spreadsheet format. Often done for reporting purposes, but not really something you do with Excel, but with the mapping solution.
Updated: October 26, 2023
Unfortunately, there is no detailed software record in the database that match this conversion.
TIFF
Files with tiff extension are bitmap images in the Tagged Image File Format. Usually having the extension TIF, it's one of the more common graphics file types.
XLS
Files with xls extension are best known as spreadsheets from Microsoft Excel. A spreadsheet is basically a grid of cells sorted in rows and columns. Each cell can contain text, numeric or formula data. Excel XLS spreadsheets can be opened in most other similar programs, such as OpenOffice.org Calc.