I got two sqls listed below,sql 1 takes bout 2 minutes when run in oracle while sql 2 was fixed to take less than 200 msecs while giving the sam eoutput.Could someone please explain me,why sql 1 was a performance killer!!

sql1:

select c.*
FROM
cuappo.CHARGE C,
cuappo.ADJUSTMENT A,
cuappo.INVOICE_ITEM I
where
C.BAN = 400077190
AND I.BAN = C.BAN
AND I.ENT_SEQ_NO = C.INV_SEQ_NO
AND (I.ESSENTIAL_TYPE = 'A'
OR 'A' IN ('A','O' ))
AND ((I.INV_STATUS = 'O'
AND
I.INV_TYPE IN ('DA','9 '))
OR
and (I.DSPT_ADJ_AMT > 0
AND
C.DSPT_TOT_AMT > 0)
AND C.BAN = A.BAN(+)
AND C.ENT_SEQ_NO = A.CHARGE_SEQ_NO(+)


sql2:

SELECT
C.*
FROM
cuappo.CHARGE C,
cuappo.ADJUSTMENT A,
cuappo.INVOICE_ITEM I
WHERE
I.BAN = 400077901
AND (I.ESSENTIAL_TYPE = 'A' OR 'A'IN ('A','O' ))
AND I.INV_STATUS = 'O'
AND I.INV_TYPE IN ('DA','9 ')
AND I.BAN = C.BAN
AND I.ENT_SEQ_NO = C.INV_SEQ_NO
AND C.BAN = A.BAN(+)
AND C.ENT_SEQ_NO = A.CHARGE_SEQ_NO(+)
UNION
SELECT C.*
FROM
cuappo.CHARGE C,
cuappo.ADJUSTMENT A,
cuappo.INVOICE_ITEM I
WHERE
I.BAN = 400077901
AND (I.ESSENTIAL_TYPE = 'A' OR 'A' IN ('A','O'))
AND I.DSPT_ADJ_AMT > 0
AND C.DSPT_TOT_AMT > 0
AND I.BAN = C.BAN
AND I.ENT_SEQ_NO = C.INV_SEQ_NO
AND C.BAN = A.BAN(+)
AND C.ENT_SEQ_NO = A.CHARGE_SEQ_NO(+)