Difference between UNION and UNION ALL ?

UNION and UNION ALL both are used to combine the results sets into one single results set, But following are the difference between the both operators.

#.	UNION	UNION ALL
1	UNION removes duplicate records from the two or more results sets	UNION ALL doen’t remove duplicate records from the two or more results sets
2	UNION  Sorts the data from the results sets	UNION ALL doesn’t Sorts the data from the results sets
3	By compare with union all, union is much less performance. Because of it must scan the result for duplicates	UNION ALL performance is more comparing with UNION