Overview: Disc structures and images
Disc structures and images preserve media files together with the organization used by a disc-based playback system.
A DVD or Blu-ray title can involve several files and navigation structures. An ISO image preserves a disc-shaped storage arrangement rather than converting that title into one ordinary movie track. These pages explain what is stored so a disc folder, image and extracted media file are not mistaken for the same playback object.
DVD-Video file structure
DVD-Video combines VOB media files with IFO navigation information and backup files inside a VIDEO_TS directory.Blu-ray file structure
A Blu-ray movie presentation uses playlists, clip descriptions, and transport-stream media files within a BDMV directory structure.Disc images (ISO)
A disc image stores a volume and its filesystem as a file, preserving a disc presentation rather than replacing it with a single encoded movie.