There is absolutely no difference between LEFT JOIN and LEFT OUTER JOIN. The same is true for RIGHT JOIN and RIGHT OUTER JOIN. When you use LEFT JOIN keyword in SQL Server, it means LEFT OUTER JOIN only.
USE Database1
CREATE TABLE table1
(ID INT, Value VARCHAR(10))
INSERT INTO Table1 (ID, Value)
SELECT 1,'First'
UNION ALL
SELECT 2,'Second'
UNION ALL
SELECT 3,'Third'
UNION ALL
SELECT 4,'Fourth'
UNION ALL
SELECT 5,'Fifth'
GO
CREATE TABLE table2
(ID INT, Value VARCHAR(10))
INSERT INTO Table2 (ID, Value)
SELECT 1,'First'
UNION ALL
SELECT 2,'Second'
UNION ALL
SELECT 3,'Third'
UNION ALL
SELECT 6,'Sixth'
UNION ALL
SELECT 7,'Seventh'
UNION ALL
SELECT 8,'Eighth'
GO
SELECT *
FROM Table1
SELECT *
FROM Table2
GO
SELECT t1.*,t2.*
FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.ID = t2.ID
SELECT t1.*,t2.*
FROM Table1 t1
LEFT OUTER JOIN Table2 t2 ON t1.ID = t2.ID
