As far as I know lignes relates only to size. Many years ago Caliber (as relates to Horology) related to size only as well. Today caliber is the form of identification for a specific movement attributed to a specific manufacturer (Rolex Caliber 1570, etc.). In fact a watch movement's "caliber" is what is registered with the Swiss Trademark office listing all of its salient characteristics (size, complications, materials, etc.). In effect it is now a form of intellectual property protection for a specific movement and its manufacturer. Hey, you asked.