Network routing is usually used on the internet and most networks rather than source routing. Network routing is used to select paths on a network where network traffic will be sent. Network traffic is sent through network nodes called routers.
With network routing the knowledge about the network layout is in the network routing devices. The routing device will choose the path of each data packet based on the destination IP of the packet. Some network routing may be static or it may use a dynamic routing protocol to update the routers with information about the state and configuration of the network.
Source routing is a different method than network routing and source routing can be used to specify the route that a packet should take through the network. The path through the network is set by the source or a device that tells the network source the desired path. It is assumed that the source of the packet knows about the layout of the network and can specify the best path for the packet. Source routing can produce some security problems.