Is Kurviger using Google Maps? What's the difference?

Kurviger does not use Google Maps but data from OpenStreetMap (OSM). There are differences between Google Maps and OSM data.
The biggest difference is that if you find an issue or something missing in OSM, you can fix the issue yourself or you can tell the community about the issue and they will help to improve it. The same applies to routing.

For more information, please have a look here: There was an issue during the route calculation or navigation, what can I do about it?