There are two ways to make leaves and grass. You can create a detail model of the leaves and grass or you can have a rectangle and apply textures with alpha maps.
If you model the leaves and grass you get better run time performance at the expense of large polygon counts which requires a lot of VRAM for dense scenes.
You can go with texture on a simple polygon model and use alpha maps to make create the shape of a leaf, which gives you a scene with less polygons, lower vram consumption for certain scenes but alpha maps are slow at run time.
I suspect that FC6 is using a lot of alpha maps for leaves and grass and may switch it out for higher res models when close up.
If you model the leaves and grass you get better run time performance at the expense of large polygon counts which requires a lot of VRAM for dense scenes.
You can go with texture on a simple polygon model and use alpha maps to make create the shape of a leaf, which gives you a scene with less polygons, lower vram consumption for certain scenes but alpha maps are slow at run time.
I suspect that FC6 is using a lot of alpha maps for leaves and grass and may switch it out for higher res models when close up.