Do you have a key column in each worksheet that can be used to compare what's
there and what isn't.
If yes, then you could use =isnumber(match(a1,sheet1!$a$1:$a$9999,0)) in a
helper column in sheet2 and =isnumber(match(a1,sheet2!$a$1:$a9999,0)) in sheet1.
Adjust the ranges and the sheet names and copy down. You'll see a bunch of
true/false's. Trues mean match.
This'll work ok if your lists have that unique key. If you wanted to compare
values in adjacent cells for each key, you could use a series of =vlookup()'s to
return the associated values.