List Referencing

I have 2 columns of info. 1 is a complete list. The other has many of the same values, but is missing a lot of the values in column one.

I am marrying the two lists to see where the data gaps are. Both lists are from different databases and I need to know which data the second DB is missing.

Currently I am lining the 2 columns up and doing it manually.

Is there a way to do this quickly as there is about 1000 records.

Thanks for your time