Net Device is the most import element in the simulation.This part is to show you the demonstration of two nodes with 4 different kind of network device.
Even a single node is able to mount a lot of network devices. How to make them work independently or cooperatively, it depends on you.
You can think it as a wire using CSMA protocol.
2. Point To Point
You can think it as a wire ... I'm not sure what it is...
There are 2 modes for the Wi-Fi network device. AdHoc and Infrastructure mode. Adhoc is able to communicate with 2 nodes, but infrastructure needs a access point as a relay point.
It's more complicated. A LTE system needs 2 extra nodes besides end nodes, those are PDN gateway and eNodeB.
You can build a very complicated network topology. But here, I just demonstrate several kind of simple connection method.