Message Bus Performance

Hi,
I have a question on the message bus (TIBCO, MQSeries ,etc) All are the famous message bus vendor.
I am still new in this area. Anyone can tell me more about this technology and what is the different from normal way of connection using the SQLNET method ? I know that this message bus is create for real time application but is that mean the conventional connection can't provide as fast as message bus ?

I can send the SQL command using the message bus and send it to a mailbox and someone need to retrieve the mailbox.

Your reply is very appreaciated. Thanks