What is the difference between these devices? Which one is used for which purposes?
They're all mentioned as "Wireless", but basicially this means the device will allow LAN connections via WiFi connections.
Brief Non-Technical Differences
A Modem is a device that connects to the internet, handling the different communication type required compared to your local network.
A Router provides a gateway (or link) between two or more networks.
A Modem Router both connects to the internet and provides a gateway between that connection and your LAN.
From the consumer standpoint, these might all be in one unit. However on the technical side
- Modem - This provides you your internet. You plugin in either a phone line, coaxial cable, fiber, or something else thats not ethernet
- Router - Distributes the internet connection over many devices. This allows you to have only one connection but many devices.
This is a very simplified answer, but is the general information.
Since there are several technical answers, here's one non-technical:
Wireless router is a router with Wireless access point. It usually has at least 4 connectors for wired LAN. Other answers explain what router is so I won't go in there. Please note that it may have wired LAN connector for modem.
wireless modem is usually combination of router with one wired port and wireless access point.
Wireless modem and router is a router with integrated modem, so instead of using separate modem, it has its own.
Wireless Router also acts as a local router spliting up the connections on the local network. Wireless Modem is what recieves the connection from ISP asi Xavierjazz said. FYI: Wireless just mean they also give wireless service. And when it say's modem router i means it provides both services. Most wireless "modems" are routers also, and most modern modems also act as a router.