The black trilogy box set is the Definitive Collection. The individual discs you have could be the Special Widescreen Edition or any of the Pan and Scan " time compressed" or standard time releases. The easiest site to find what you have is http://www.blam1.com/StarWars/
If you do have the Special Widescreen Edition as well as the Definitive Collection, I am sure there would be huge interest in an X9 transfer or two. There is also a possible project to get "ripped" audio from the Special Widescreen Edition and Empire Strikes Back is still on the wanted list.