The Geographic Determination Library allows you to determine a geographic region that describes the maximum probable variance associated with the geocode. This geographic region is referred to as a geo-variance buffer or surface. Once you have this surface area created, there are a number of functions available in GDL that allow you to make comparisons between it and other geographic features.
There are essentially two types of comparisons available to you, near/far distance comparisons and polygon overlap comparisons. Distance comparisons are useful when you need to determine with great confidence whether or not an address is located within a certain distance of another feature. Polygon overlap comparisons are useful for determining whether or not your geocoded address is located within another polygon.