In short, when you go to those websites they tell you what your Wide Area Network (WAN) IP address is. This is given to you by your ISP, in most cases. Other examples would be a school/work network, coffee houses etc. Internet service providers 'own' a long list of a specific IP ranges that they are allowed to assign to their customers. But since they are registered to that company and not to you, searching for that IP will result with their city location, and sometimes physical address if they allow it.
Your personal router turns your house into a Local Area Network (LAN). All computers connecting to it are assigned an IP address based off your routers preset default IP range. In most cases this is 192.168.1.1 and when you run ipconfig your IP address will say something similar to that. However, all traffic that goes to the internet still has to go through your ISP where you are being branded by your ISP's IP range. In order to scan your home network you will have to do it from home, or within your wireless network's range.
I'm working on another article btw that is going to explain IP addresses in depth and how tracing works.
"The quieter you become, the more you are able to hear..."
"Drink all the booze, hack all the things."