"Server" vs "Data Source" in connection string

... There is no difference between Server and Data Source as they represent the same thing for SQL Server : the full name of the SQL Server instance with the syntax "MyComputerName\MyShortInstanceName" , potentially including the port used by the SQL Server instance to communicate.

Reference: http://social.msdn.microsoft.com/Forums/en/sqldataaccess/thread/7e3cd9b2-4eed-4103-a07a-5ca2cd33bd21

For the full list of all of the connection string keywords, including those that are entirely synonymous, please refer to the SqlConnection.ConnectionString documentation:

These are all entirely equivalent:

• Data Source
• Server
• Address
• Addr
• Network Address

They are synonymous - you can use either one.

That is - as far as the framework is concerned, they are the same.