They are two different things, but you can have both at the same time. An open roof deformity usually occurs after filing down a bony hump. The nasal bones are like the roof of a house. If you remove the top of the roof, you will have an open space there between the two nasal bones. That's why after taking down a bony hump, one usually has to make cuts in the nasal bones (called osteotomies) to bring the bones inward and "close the open roof."An inverted V deformity is usually a result of collapse of the middle third of the nose. The upper lateral cartilages are attached to the undersurface of the nasal bones by fibrous/ligamentous attachments. If the upper lateral cartilages lose their support and attachments to either the nasal bones and/or nasal septum, they can drop down causing a visible demarcation between the nasal bones and upper lateral cartilages/middle third of the nose. That demarcation usually looks like an upside down "V".Unfortunately both can occur concomitantly or in isolation. I hope this helps. Best of luck.