It depends on the application. Blu Ray holds more information that a normal DVD as has been stated therefore picture can be shown at a higher resolution e.g. 1080p given the right TV equipment, however, it is a really expensive process to remaster a movie that was made 20 years ago and in digital terms, it's easy to go backwards in terms of quality, but to polish a movie is like polishing a turd - it'll still look crap. It's the old LP's vs CD's argument.