Comparing Spreadsheets

I have one spreadsheet that is a download of a query I pulled at a certain date. Then, I have another spreadsheet that is a download of a query I pulled today. I want to compare the two spreadsheets and add to the first spreadsheet those accounts listed on the second spreadsheet that are not listed on the first. Is there an easy way to do this?

If you have an account number you could use a vlookup on the second spreadsheet against the first.
This will show if the account has appeared in the first set of data.

Then you can filter against the account numbers that come out as N#A (the ones that were not on the first set of data) and only paste these onto the sheet with both dates.

Try to open a new sheet, press DATA->CONSOLIDATE, then add all the ranges. in the USE LABELS IN THE section, check the TOP ROWS and LEFT COLUMN.

The resulting table you will get in the 3rd sheet will be combined report.

You can also make a pivot table using multiple concolidated ranges.

Here is the issue that I am running in to. While I am trying to compare accounts, I have over 1500 of them so doing it manually would take alot of time. Furthermore, there is a alot of data in in the following cells tied to each account that I need to keep. Is there anyway to make the computer do the work here?

You could export both the spreadsheets to Access via Tables - import and then compare them by creating the required queries.