SQL query using not equal to or not exists

E.g.

DECLARE @Sample TABLE
    (
      ClientName VARCHAR(255) ,
      Outputs VARCHAR(255)
    );

INSERT  INTO @Sample
VALUES  ( 'ABC', 'SOSP' ),
        ( 'ABC', 'Pre Start' ),
        ( 'ABC', 'BA' ),
        ( 'XYZ', 'SOSP' ),
        ( 'XYZ', 'BA' ),
        ( 'DEF', 'SOSP' ),
        ( 'DEF', 'BE' ),
        ( 'QWE', 'SOSP' ),
        ( 'QWE', 'Pre Start' );


SELECT  S.ClientName
FROM    @Sample S
EXCEPT
SELECT  S.ClientName
FROM    @Sample S
WHERE   S.Outputs IN ( 'BA', 'Pre Start' );

SELECT  DISTINCT
        S.ClientName
FROM    @Sample S
WHERE   S.ClientName NOT IN ( SELECT    S.ClientName
                              FROM      @Sample S
                              WHERE     S.Outputs IN ( 'BA', 'Pre Start' ) );