While setting up the creation method for your SubD, you can also change the display mode. The top three icons change display from Display Control Polygon, Display the SubD, and SubD Mesh with the Control Edges and Vertices. The bottom three icons allow you to change the visibility of the Faces, Edges, and Vertices. Sometimes you may want to see the shape without the edges.
The images are from left to right: Control Mesh, SubD Mesh, SubD Mesh Faces plus Control Cage, Control Cage box with additional subdivisions.
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