It is not always clear how the street classifications are separated from each other. Here you can get an overview.
In Germany, roads are divided into different classes that reflect the area of responsibility and size. In the vialytics web app, a distinction is made between the common classes of federal roads, country roads, district roads, residential roads, access roads and side roads.
This distinction is based on the information tagged to the respective street in OpenStreetMap. More information about the distinction of streets can be found in this article.