Switch:

computers can connect to switch using ethernet cables it forwards incoming traffic to specific device based on mac address only it has mac address table of all devices connected

Router

It is an intermediary device
intermediary device like router works with only network layer,data link layer,physical layer data only it will not touch other layers.

cables

ethernet cables divides into 2 categories
1.ethernet straight through: used to connect diffrent type of devices
2.ethernet cross-over: used to connect two devices of same type
fibre optic cable