SQL Server World

Implicit Conversion:

Implicit Data type conversion is done by SQL Server without notifying user.

Explicit Conversion:
Explicit conversion is done by user either by issuing Convert or Cast function command. An example of explicit conversion would be converting Date data types to the format you want .

SELECT GETDATE(), CAST(GETDATE() AS time(7)) AS ‘time’ ,CAST(GETDATE() AS date) AS ‘date’
,CAST(GETDATE() AS smalldatetime) AS ‘smalldatetime’ ,CAST(GETDATE()AS datetime) AS ‘datetime’
,CAST(GETDATE() AS datetime2(7)) AS ‘datetime2’ ,CAST(GETDATE() AS datetimeoffset(7)) AS ‘datetimeoffset’;

For more information, see http://msdn.microsoft.com/en-us/library/ms187752.aspx