FYI, a voxel (volumetric-pixel) is a 3D rendering primitive which is a competitor of the polygon (yes there is other primitives like elipsoide[0]). A point cloud carrying whatever augmented information isn't in itself a voxel model. Ultimately, a voxel is a voxel when it is rendered as such: when this is the 3D primitive used to support/make the rendering.

So are minecraft lanscapes made of voxels? No, these are polygons.

[0] http://www.hardcoregaming101.net/ecstatica/ecstatica2-6.jpg