Let me try to quantify the differences (and where I write HD Mesh, there UHD Mesh would apply equally - generally speaking). And with the XP11 default Global Scenery I mean the one replaced with public beta one (later this might change).
1.HD Mesh Scenery v3: older data (approximately 2 years old) - XP11 default: newer OSM data (August 2016)XP11 default has updated
landclass data for many regions (compared to HD Mesh Scenery v3)
2.HD Mesh Scenery v3: older autogen placement algorithms and no special European roads during scenery generation (XP11 default has
a slight edge here - at least urbanized areas might look better)
3.HD Mesh Scenery v3 has much higher resolution Mesh (this has NOT been changed in XP11 default do to scenery size constraints!)
4.HD Mesh Scenery v3 has much more accurate landclass representation (even if its based on older data as described above) because of
its higher res mesh (landclass is bound to mesh triangles)
5.HD Mesh Scenery v3 has older (because of older OSM data) but more accurate coastlines (rivers, lakes, ocean) as XP11 default needed
to simplify vectors ... again because of scenery size constraints.
So, in the long run (especially to iron out the first 3 "disadvantages") I will possibly release a HD Mesh Scenery v4 (and likely some similar update to UHD Mesh). .........取材自http://forums.x-plane.org討論串供你參考.