There is no reason to make a comparison between a cable modem and a router, as they are parts serving different purposes in an Internet network. However, the deliberate comparison made here, serves the purpose of explaining the working of these two devices that complement each other.
Difference in Functionality
Modem is short for 'Modulator- Demodulator'. It decodes analog carrier signals into digital ones and converts digital ones, back to analog. It makes the transmission of digital data over media like telephone or cable lines possible.
Many cable TV companies also provide Internet access and the contact to this Internet connection is made through the modem. You could also have a DSL modem, which makes the Internet connection through the telephone line.
While the cable modem is the primary receiver and sender of data to the Internet, the router serves the function of distributing that data over a wireless network.
It directs data to multiple computer terminals and is the main component of any wireless Internet network. It functions like the receiver of a cordless phone. Only, instead of voice data, it transmits and receives modulated digital data on radio frequency carriers.
Some of the best routers can connect and handle more than 50 users at a time. So, in conclusion, to put it a bit crudely, the modem is the main supply line of the Internet connection, while the router is the distributor of the data bits over air (through radio link), giving you an unplugged Internet experience.
If you want to set up a Wi-Fi Internet connection in your house, then you need to set up the cable modem and the wireless router. The modem's setup is quite straightforward. It involves three or four wire connections.
It generally has three connections to be made. One is the power connection which serves the electrical power required for functioning, the second is the cable Internet connection or DSL connection, coming from the Internet company, and the third is its connection with the router.
In case, you are not using a router, the modem is directly connected with the appropriate computer port. Cable modem problems are easily resolved by reconfiguring them and they are quite maintenance-free.
A wireless router setup involves two main connections. First is the incoming line from the cable/DSL modem and second is the power cord connection. Once the hardware connections of the modem and router is made, the last part is configuring them, to establish a wireless connection with your computer (which has to be fitted with a Wi-Fi card).
In the configuration part of this installation, you will have to temporarily connect the modem with your computer, run the installation disc, configure, and then remove it. To configure a router, you will have to temporary make a connection.Nowadays, you also get a combination, in the form of a cable/DSL modem, with the router built into it.
This type can do both jobs and reduce the hassle of handling the setups of two devices at a time. Router problems are mostly related to limited range of access and low signal strength. The range problems can be solved using antenna boosters, that improve signal quality and range.