I'm not sure, but that "smooth" thing in Maya sounds about right. If it is, then what I said probably applies to it.
LODs are level of detail. Basically when a model(let's say a tree, since speedtree does exactly this too) is close up, you see it in high poly glory(let's say 10,000). Then at some distance, you see a lower poly version of it(5,000), and further yet, the tree only has maybe 1,500 polys. Finally, in the distance, it may get converted to a single billboard tree(works well for things that aren't really animated).
Generally if your game will do this, then you may create a super high poly version first in ZBrush. Then create a "normal" version, which you use the ZBrush version to bake normals onto. Then you can lower the polys either directly or using a tool in order to get the lower poly versions.
The issue we currently have is just that you are going the other direction, which is not as common from what I have seen.