I think there is some confusion as Daz has added both sub-D and LOD to Studio.  Just as with Poser, sub-d can be turned on to increase the apparent detail of a mesh at render time.  If they are using different techniques to do this, then different results can be expected.  It seems that for LOD, the multiple resolutions are seperate meshes that are a part of the same figure.  The idea of this is that you can pose and set up your scene with low res figures while the software will use the high res figures at render time.  Apparently it is possible though to export a figure at a chosen level of detail.  So if you exported (or only had) the medium res version of your figure, you could use the smoothing to approximate the higher res mesh.