In the text the term connection oriented service is used to describe a transport layer service and connection service for a network layer service Why the subtle shades in terminology?

In a virtual circuit network, there is an end-to-end connection in the sense that each router along the path must maintain state for the connection; hence the terminology connection service.

In a connection-oriented transport service over a connectionless network layer, such as TCP over IP, the end systems maintain connection state, but the routers have no notion of any connections; hence the terminology connection-oriented service.