WiFi cable modems have wireless routers built-in to them. They are more commonly referred to as a modem router combo, and sometimes a gateway. They provide a wireless signal to many devices like TVs, PCs, game consoles, and more. The distance and speed the router operates depend on two main factors. The first is on what spectrum the WiFi cable modem operates on. Secondly, how the device is built itself, the number of antennas, and so forth.
WiFi modems are often more expensive than a traditional modem. This is because of the built-in router. WiFi modems also take up less space which some find more convenient. The most commonly used wireless today is wireless AC. Up and coming is wireless AX or WiFi 6. This makes wireless N technology out of date. Wireless N modems should be avoided at all costs. The newer technologies offer faster WiFi speeds and further wireless transmissions.