Answer Posted / praveen k. agrawal

union is used For select distinct values from two tables
where as union all is used For select all values including
duplicates from the tables.

For Example Table X contain values(a,b,c) and Table Y
contain values(c,d,e)
In Case Of Union we will get Result-a,b,c,d,e
and other hand (Union All ) we will get-a,b,c,c,d,e.

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