I have both maps on the Oregon 750t. There are differences when planning on the computer. When you enter a start and end point, the Europe map creates a different route than the Switzerland map. I haven't had the device and the map long enough to be able to judge the qualitative difference. I could only make an assessment in a few weeks.
However, I planned a route with the Europe map and the Switzerland map and then planned the same route with the wanderung.ch website, where you can plan hikes on hiking trails. This route pretty much matched the route from the Switzerland map (I didn't go into detail), the deviations from the route with the Europe map were significant.
The Europe map has only roads and paths and special points, the Switzerland map is naturally more detailed and also has houses (and huts) and contour lines, which the Europe map does not have, plus it differentiates the roads and paths better (drawn out line, dashed etc.) But a legend is missing on both maps. I prefer to use the Switzerland map for planning because it is more detailed. But the Switzerland map is from 2016 and the Europe map from 2019.