hI , this is a self join

SELECT F.PARTNUM, F.DESCRIPTION,
S.PARTNUM, S.DESCRIPTION
FROM F.PART, S.PART
WHERE F.PARTNUM=S.PARTNUM
AND F.DESCRIPTION <> S.DESCRIPTION;


and how the book says F.DESCRIPTION <> S.DESCRIPTION
,if it is self join , so it means everything is the same?????
thanks