Find Items in one column that are not in another column

1. Select the list in column A
2. Right-Click and select Name a Range...
3. Enter "ColumnToSearch"
4. Click cell C1
5. Enter this formula: =MATCH(B1,ColumnToSearch,0)
6. Drag the formula down for all items in B

If the formula fails to find a match, it will be marked #N/A, otherwise it will be a number.

If you'd like it to be TRUE for match and FALSE for no match, use this formula instead:

=ISNUMBER(MATCH(B1,ColumnToSearch,0))

If you'd like to return the unfound value and return empty string for found values

=IF(ISNUMBER(MATCH(B1,ColumnToSearch,0)),"",B1)

Here's a quick-and-dirty method.

Highlight Column B and open Conditional Formatting.

Pick Use a formula to determine which cells to highlight.

Enter the following formula then set your preferred format.

=countif(A:A,B1)=0

Select the two columns. Go to Conditional Formatting and select Highlight Cell Rules. Select Duplicate values. When you get to the next step you can change it to unique values. I just did it and it worked for me.