In the widescreen Blu-ray, when Jack draws Rose on the couch, you see her face and his hands. In the Open Matte version, you see the entire ceiling of the stateroom, Rose’s bare foot resting on the chair, and the full prop lamp above them. During the sinking, you see more water at the bottom and more falling debris at the top. For purists, the Open Matte offers 30% more vertical image. In the search string, this is the openmatte flag.
Your query describes an version of Titanic that combines a Blu-ray source with open matte video from another transmission. While technically interesting, it’s not a legitimate product. i download portable titanic1997openmatte1080pblura