I'm helping a colleague who receives a monthly report which grows by about
25K rows per month. There is one field from which we generate a list of
unique values using AdvancedFilter; the resulting list is about 10K rows.

On a month to month basis, we need to compare the previous unique list to
the current unique list, and create a third list that contains ONLY the new
values that show up in the current list that were not present in the previous
list.

I can do this by looping through either list and doing a Application.Match
against the other list, and writing those values to a new sheet, but I was
wondering if there is a cleaner way to do this. I was amazed when I learned
how to use AdvancedFilter to create the original unique list, so I figured
I'd check here to see if there was any similar built-in functionality (or a
criteria I could use with AdvancedFilter) to generate only those values that
aren't in both lists.

Thanks for enlightening me!
Keith