What is the difference between a router and a switch?

A switch works at layer 2 the data layer and bridges between network segments within a broadcast containment area. A router works at layer 3 the network layer and moves traffic from the source broadcast containment area to the destination broadcast containment area if appropriate.

A router does NAT (Network Address Translation), a switch or hub does not.

So a router enables many computers to share one public internet address. The computers will each think they have a private/local IP address (often 192.168.x.x or 10.x.x.x). When one of the computers sends out a message to an Internet site, the router will change the "from" IP address in the outgoing packet to be the shared public IP address, and when the reply comes back the router will adjust the "to" IP address to be the correct computer's private/local IP address. (The router uses "port numbers" to keep track of which packets go to which computers.)

Router - Layer 3

Switch - Layer 2

both of them are used to inter-connect computers the only difference is a router can give/manage ip address of your workstations.