While driving, you need to be able to read road names quickly and clearly see which road you will take next. The default text size might not be big enough, this is why Maps Pro can have bigger texts and roads by changing the "zoom factor". There are several options, from 1x (default) to 3x. These options can be found in Menu > Help > Options > Vector Maps zoom factor.
For instance, here is the Vector Map with the default zoom factor:
And when you set the zoom factor to 2x, for the same zoom level:
And 3x zoom factor: