SELECT *
FROM tblA LEFT JOIN tblB ON
tblA.[Address] = tblB.[Address]
WHERE (((tblB.Address) Is Null));[code]
If you get any results, you'll know something is different. You can look at the results and select a field or 2 to investigate the record(s) further.
You can also try the unmatched query and reverse the tblA, tblB to check tblB not in tblA.
Good luck.