How can I compare two columns in Excel using Vlookup?

Answer 1

You can use Conditional Formatting to find duplicates in a selected area.  It's an option from the Highlight Cells menu under Conditional Formating.

Answer 2

If you want to compare two columns, an easier approach might be just to directly ask Excel to compare them value by value. For example, if I write =A1=B1 then Excel will return either TRUE or FALSE to tell me if the values in those two cells are identical (TRUE) or not identical (FALSE). 

 

If you use VLOOKUP instead... let's call your lists List 1 and List 2 that you are comparing. You can search each value in List 1 as your key value (argument 1), then tell VLOOKUP to find it in the table array that is List 2 (argument 2). You don't really care what value column it should return (argument 3), but you probably do want an exact match (argument 4 = 0 or False). Now, with that VLOOKUP, if you get an error message then that likely means that the value from List 1 does not appear in List 2. However, you won't be able to see the reverse (values in List 2 that do not appear in List 1).