Which query is best and why?

Hi all
The following two queries are givin the same result.but the last query returns rows quicker than the first one.
can some one tell me the difference in the logic
SELECT E.ENTITLEMENT_ID,EP.ENT_PARTY_ID ,EP.PARTY_ROLE FROM
ENTITLEMENT E
LEFT OUTER JOIN
ENT_PARTY EP
ON E.ENTITLEMENT_ID = EP.ENTITLEMENT_ID
AND EP.PARTY_ROLE = 'ENDCO',
CONTRACT_SITE,
PRODUCT
WHERE (E.PRODUCT_ID = PRODUCT.PRODUCT_ID)
AND (E.CONTRACT_SITE_ID = CONTRACT_SITE.CONTRACT_SITE_ID)
AND UPPER(CONTRACT_SITE.SITE_PUB_ID) = N'PTA18DEC200616619')
ORDER BY E.ENTITLEMENT_ID
SELECT E.ENTITLEMENT_ID,EP.ENT_PARTY_ID ,EP.PARTY_ROLE FROM
ENTITLEMENT E
LEFT OUTER JOIN
ENT_PARTY EP
ON E.ENTITLEMENT_ID = EP.ENTITLEMENT_ID,
CONTRACT_SITE,
PRODUCT
WHERE (E.PRODUCT_ID = PRODUCT.PRODUCT_ID)
AND (E.CONTRACT_SITE_ID = CONTRACT_SITE.CONTRACT_SITE_ID)
AND UPPER(CONTRACT_SITE.SITE_PUB_ID) = N'PTA18DEC200616619')
AND EP.PARTY_ROLE = 'ENDCO'
ORDER BY E.ENTITLEMENT_ID

Performance would probably improve further if you included proper JOINs to the CONTRACT_SITE and PRODUCT tables, instead of joining in the WHERE clause.
You should keep the filtering in the WHERE clause, and not apply it in the ON part of a JOIN. On the other hand, that is probably the reason for the difference in performance. Still, use the FROM clause for JOINing tables, and the WHERE clause for filtering.
Another improvement would be to drop the UPPER() function around SITE_PUB_ID, since it is pointless unless it is a column with a case-sensitive collation. If there is an index for SITE_PUB_ID, the use of the UPPER() function actually forces SQL Server to ignore the index.