Quick Primer - Ethernet is a bus protocol, multiple devices can be on the same electrical cables. Although the vast majority of ethernet you will see is point-to-point links, it’s important to remember this

• Hub (layer 1 - it could just be a cable) - Everything can be seen by everyone, every packet goes everywhere. (Hard to buy a hub nowadays everyone sells switches)
• Switch (layer 2 ethernet address aware) - Packets are only delivered to the ports of the switch with the corresponding hardware address. So Traffic from port 2 - to port 14 only goes on those two ports, and doesn’t get seen by all the other computers, this reduces congestion
• Router (layer 3, IP address aware) - apply rules at the IP level to determine what goes where, i.e. the send traffic to the internet, or deny traffic from the printer to the internet.

The more logic, switching, throughput, and power delivery something has, the more energy it consumes and the more heat it needs to dissipate.

Managed Switch - Allow for fine grained control of ports, which traffic goes where, manually turning things on and off, vlans, etc… more then just a MAC address lookup table.

The interface for switches and routers can be serial ports and CLI, all the way to fancy web guis. Usually the more pretty the interface the less flexible it is and the more basic the functionality it delivers.