|There is no comparison that can be made between an ADSL Modem and a router so whatever you heard is probably falae. They two completely different devices doing two completely different jobs. Sometime the two devices are combined into a single box giving you a Modem/Router. Nearly all of the combined Modem/Routers are ADSL. |
The advantage of this as a combined unit is often cheaper than two separate units and there are less cables to worry about and only a single power supply. It makes no difference to the speed at all. That is determined by other factors.
A USB modem is designed for a single computer only. I have never seen a router that can take a connection from a USB Modem. For that you need an Ethernet Modem.
Routers without Modems are neither Cable nor ADSL. They are just routers that accept an Ethernet input. It is the Modem that has to be Cable or ADSL specific. and if you want to connect it to a router, with an Ethernet output.