Comparison between different switching techniques
If a connection (path) between the origin and the end node is established at the beginning of a session we are talking about circuit or packet (virtual circuit) switching. In case it does not, we refer to message and packet (datagram) switching. On the other hand, when considering how a message is transmitted, if the whole message is divided into pieces we have packet switching (based either on virtual circuit or datagram) but if it does not, we have circuit and message switching.
more details
http://lsiwww.epfl.ch/LSI2001/teaching/webcourse/ch11/ch11.4.html