The Google Maps API provides its own geocoder,
GClientGeocoder. While this works well for most inputs, it is forced to provide inaccurate results for the location of postcodes due to the licencing restrictions on the data - the difference can be as much as several miles.
By using the Integr8 Geocoding service, you have a licence to access the postcode location data provided by the Royal Mail. If you are also using Google Maps API, we provide our own drop-in replacement for
GClientGeocoder that will use the Integr8 Geocoding service for finding the location of postcodes, and the Google Maps API service for finding other locations.