Maya creates NURBS surfaces corresponding to the subdivision surface and groups them.
To manipulate the resulting group of NURBS surfaces
Stitching makes the patches deform as one surface, but the patches are still regarded as separate surfaces when you assign materials. You can also use the other stitching operations under the Stitch submenu.
Attaching creates a new continuous surface and is regarded as one surface when you assign materials. You must apply Attach Surface repeatedly, one patch at a time. Be aware that the order you attach patches affects the placement of any textures you might apply to the surface.