meh, im sure poepl in different areas say things differently. like even sometimes i saw, woah, you almost hit your head on the roof, when i mean the ceiling. not anything worth argueing about thats for sure.
attually a roof is the layerof material to keep the weather out ofter slope to drain rain a ceiling is mostly horavontal to insulate the building or used as the floor above this here is the roof as it is the underside of the outside roof