I gather that Poser will handle some .obj files that other programs will not. And does a few other things differently. There's probably some info out on the web, but three aspects come to mind. 1: Poser meshes don't require all faces to be triangular. 2: Poser tends to smooth edges, though later versions can switch this off for an object, so Poser meshes might be made with with a few features to limit the smoothing. 3: Poser uses a different scale. I suppose every rendering program has some little quirks in how they handle a mesh.