Here's a better way:

SELECT 'IN A NOT B' location, a, b, c, d, ...

FROM tablea

EXCEPT

SELECT 'IN A NOT B' location, a, b, c, d, ...

FROM tableb

UNION ALL

SELECT 'IN B NOT A' location, a, b, c, d, ...

FROM tableb

EXCEPT

SELECT 'IN B NOT A' location, a, b, c, d, ...

FROM tablea

No parentheses this way.