MINUS Operator

Mam 2 tabele A i B.

SELECT COUNT(*) FROM (SELECT * FROM tableA)

zwraca 389

SELECT COUNT(*) FROM (SELECT * FROM tableB)

zwraca 217

SELECT COUNT(*) FROM
(SELECT * FROM tableA
INTERSECT
SELECT * FROM tableB)

zwraca 0

SELECT COUNT(*) FROM 
(SELECT * FROM tableA
MINUS
SELECT * FROM tableB)

zwraca 389

SELECT COUNT(*) FROM 
(SELECT * FROM tableB
MINUS
SELECT * FROM tableA)

retuns 89

Czy ktoś może wyjaśnić, dlaczego ostatnie zapytanie zwraca 89, a nie 217?