Circuit switching or "connection-oriented data transmission":
path must be decided before data transmission starts;
completion of transmission can be faster because less
overhead is used for routing data units;
if the connection breaks so does transmission of data.
Packet switching or "connectionless data transmission":
at start of transmission no need to worry about establishing a route;
ability to send data packets over any route means transmission
can be more reliable;
completion of transmission can sometimes be subject to delays
because packets may have to be received over different routes
and must always be re-assembled into correct sequence.