Good question!A wireless modem provides a way to connect to the internet through an Internet Service Provider (ISP). In the "old days", if you wanted to connect to the internet, you had to have your computer connected to a modem that had access to a telephone line to dial in to your ISP for an internet connection. Modern technology allows you to use a cell phone modem to do the same thing. A cell phone modem is called a wireless modem. So you can take you computer, usually a laptop computer, anywhere there is cell phone service and connect to the internet, like a cell phone dial up connection. A wireless modem allows one computer, usually a mobile computer like a laptop, to connect to the internet from just about anywhere that there is cell phone service. Some people use wireless modems to connect their home PCs to the internet because there is no other service available at their homes.A wireless router is a way for you to share one internet connection, usually at a home or small office, with multiple computers. So if you have a DSL Connection or Cable Modem connection or fiber (FiOS) connection at your house, you can share this high-speed connection with multiple computers at your house or small business.For instance, my laptop has a wireless modem so that I can access tha internet from just about anywhere when I travel. But at home, we have a wireless router that allows our four computers to share the same high-speed connection so that each computer has internet access. We can't install an ethernet cable for each conputer, so we use the wireless router to share the connection.In Summary...A wireless Modem is usually used to connect one (mobile) computer to the internet by a wireless dial-up connection. Usually a laptop.A Wireless Router is used to share one high-speed internet connection with multiple computers where it is not practical to run network wires. (Usually in a home or small business) Each computer would need to have a wireless Network Interface Device to access the wireless network.I hope this helps to answer your question.Troy Downing