DV Stands for Direct Vision which is the name Bolex first came up with to identify there Reflex lenses before H16 RX when they first designed the Reflex Camera system.
There is no difference between this lens at all and the H16 RX. This naming convention of Reflex lenses if you see a lens marked as such tells you it was one made in the very first years of manufacture of Reflex Lenses and probably supplied for use on some of the early H16 Reflex cameras
