I've been hunting around Technet and MSDN and haven't found an answer to what
the differences are between these two versions of Excel. Does anyone out
there know?

I have a grouping subtotaling routine that works on one machine and not in
another. The machine with 11.8307.8211 is a Vista machine and it works as
expected here, the 11.8169.8172 is an XP machine and it doesn't work as
expected.

The code is run from Access 2003 and uses the v11 Excel library to generate
the spreadsheet and apply some grouping to it.