Router:
works on third layer i.e Network Layer.
Does path selection, routing etc.
Creates multiple collision domail and multiple broadcast 
domain.

Switch:
works on second layer i.e datalynik Layer.
Does framinng.Error Detection etc.
Each port on the switch has a seperate collision domain.
It has single broadcast doamin and multiple collision 
domain.

Hub:
It works on physical layer.
It simply forwards the data to each port of it.
Its a non intelligent device.
Has Single collision Domain and single broadcast domain.