Q: what is common service used by Apple/Google Map

Macs do not have a GPS in them. So they cannot typically give a location with absolute accuracy.

Instead, typically WiFi is used to triangulate the location, based on a database of known WiFi hotspots. Accuracy depends on the density of hotspots in your area, as well as the quality of the data.

Which could explain why your location is off by a couple houses. +/- 100 feet is probably pretty good for WiFi, honestly.

I answered your question. Neither Apple nor Google will say specifically what service they're using. But they are using a wifi location database. An example is Skyhook:

http://www.skyhookwireless.com/submit-access-point

This Wikipedia article says that Google maintains its own proprietary WiFi location database:

http://en.wikipedia.org/wiki/Wi-Fi_positioning_system

I also have the same issue.