Hi Martin, well it's more like one is a "realtime display mesh" meant to be used for making a shaded display while modeling inside of a 3D viewport. It's overall tuned just for that purpose and takes some shortcuts with the mesh construction.

If you want to do something more "permanent" with the mesh like use it to produce a rendering or 3D print or something like that, then that's what the export mesher is for, it produces a mesh in a more careful way to make it have a higher quality structure.

The higher quality export mesh takes longer to calculate than the "realtime display mesh" - that's one of the reasons why there are 2 different mechanisms, because when you are just doing modeling you probably don't want to wait around extra time every single time you do any kind of model edit. So it helps make modeling have less hiccups just in your general workflow for the meshing there to be prioritized on speed.

So it's not that one is a "NURBS mesh" - it's that one mesher produces results more quickly but messier, and the other produces polygons more slowly yet higher quality.

If the mesh is going to be used for some kind of more involved operation like producing a final quality rendering, then that's when the "slower but higher quality" mesher makes more sense to be used.

If the mesh is going to be used only for the display of stuff on the screen while modeling only, then that's when the "faster but messier" mesher works better.


- Michael