Macro to Search Another Workbook, Alert on Discrepancy

[Smiles_Bot]

I have two workbooks, one with a listing of a few hundred existing locations that are assigned a unique number, and a second spreadsheet with some of those locations hand keyed. I am hoping to create a macro to search the first workbook for the location numbers listed in the second workbook, then alert me to any discrepancies (possibly a color change in the cell containing the number in question, or a 'pop-up' box).

I'm sure there is a way to do it with a formula, however I need to leave the cells simply as text for the individual that uses the sheet next.

Thank you in advance!

 

[Smiles_Bot]

Conditional formatting would work great if I could have my data all in one spreadsheet, but I receive new ones each month. So I think macro would be the way to go, correct?