- Original - A specimen that can be shown to be in the original as-built configuration, or as modified by the user, that remains unaltered from the time it ended operational service.
- Restored original - (Restoration): An artefact composed of at least 50% original components (by surface area or volume) and the remainder returned to accurate early condition made with the same materials, components and accessories.
- Replica - A reproduction built by the builder of the original artefact in part or in total. If it’s got original bits - Replica with some Original Parts.
- Reproduction - A reasonable facsimile in appearance and construction made with similar materials, and having substantially the same type mechanism and operating systems
- Look Alike -
- Mock Up (full scale model) -
Adapted from: Robert Mikesh, former Senior Curator of the National Air & Space Museum, in "Restoring Museum Aircraft"