Hop - Hop -DLL
Host to host -NL
End to end -TL
Now to communicate between Hop to hop mainly MAC is required by the host because they are present in same network. Hence we know that DLL operate at MAC.
Host to Host connectivity is different from end to end in sense that Host to Host between two Devices and not the actually process. Therefore devices can be uniquely identified by their IP address in entire world hence IP is required to communicate between two host
Now coming to point of process to process now process resides within a particular host and for them to communicate port number are required which is added at TL.
Now clearly host to host is different from process to process because the actual process which want to communicate with another process of some other host is only possible by socket address (port +ip)
Hope your point is clear