When we talk about the difference between router & switch,  we always try to understand in perspective of OSI Model.

You should have basic knowledge about OSI Model.

There are 7 layers in OSI Model :

1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

Switch is a device that works on Layer 2 of OSI Model (Data Link Layer) , you can use switch to connect different end devices like computer, laptop & printer in a single network.

• May be one question arise in your mind, why switch is Layer-2 device ???
• Because Switch Uses layer-2 information (MAC Address) in order to transit traffic from one end to other end.

Router is a device that works on Layer 3 of OSI Model (Network Layer), You can make communication in between different networks by connecting them with a router.

• Router uses Layer-3 information (IP Address) in order to transit traffic from one network to another.

In a layman language, you can say switch is use to connect devices within a single network & routes is use to connect two or more different networks.