Terminology is pretty loose. There are several password levels.
a) the password which allows you to access your router setup pages
b) the user name and password for accessing your ISP (the internet) which is usually set in the router's WAN section (often by your ISP)
c) the wireless security passphrase (for WPA) or the passphrase and associated HEX translation (for WEP) which are set at the router and have to be offered to the computer's wireless adapter interface or Windows Wireless Connection. These can be referred to as Security Key or Network Key.