With wireless systems, you can connect on a Local Area Network, a vast area network, and the internet minus the actual connection of wires like UTP cables. A wireless modem is a device that can connect to a wireless network as supplied by an ISP.
When you connect to a wireless modem, you are granted access to the internet when your ISP signal is present. WiFi routers, on the contrary, are devices that perform the same functions as a normal router, only it is done wirelessly.
When information is delivered from one network to another, routers supervise the activity and guide the data packets to the appropriate location utilizing the best way to go. With wireless features, WiFi routers can carry out the necessary functions through radio signals alone.