Why not just do a vlookup on each list  against the other? For example, if one
list begins in A1 on Sheet1, and the other list begins in A1 on Sheet2, you
could enter this formula in B1 on Sheet1:

=VLOOKUP(A1,Sheet2!A:A,1,FALSE)

and this formula in B1 on Sheet2:

=VLOOKUP(A1,Sheet1!A:A,1,FALSE)

On both sheets, copy the formula down for as many rows as you have data. The
formulas which return #N/A are the records not found on the other list. You can
sort by column B to put all the #N/A together.