The Nomenclature we assign to objects and events does not materially alter the events, or the objects.
"Disc Burst". Fair, but I see it as a large object "disintegrating" into smaller pieces, and then subject to release from high pressure environment, making the pieces "shrapnel"
"Case Burst", ok, not 'wrong' but the case "blew up" because it could not contain high Energy Gas and chaotic masses within.
"Explosion", Here, 212Man, is an example of your very definition of explosion.
"Explosions are caused by the release of high pressure Gases-Either through Combustion or release of Pressurized Gas". Your quote, and it fits well the circumstances as evidenced by the images and statements?
Language in the AD's suggest a possible failure of the Splines on the LP Shaft, the mechanism is unclear, no diagrams. If an oil fire, it is reasonable to assume high pressures in the IP LP shaft passage, which migrates aft to impinge on the aft side of the IP Wheel. The wheel is containing high pressure on its aft face, and with additional pressure in the cavity from the "fire", it is overstressed 'forward'. If this additional Heat/Pressure had heated the hub area of the Disc to plastic, any resistance to shear at its Shaft would have been asymmetrical, and subject to chaotic pressures in the IPLP cavity. The release of the wheel at the hub and fracturing at the radials may have been the first "Bang", followed by penetration of the Case and release of the Cavity contents to the airstream, the second "Bang"?
It is also possible the Cavity release was the first Bang; the disc "Burst" and the Cavity release may have been too close to separate audibly, and the second was the penetration of the wing.
In any case, this is simply conjecture, nothing more. I think we have the precise nomenclature sufficient to understand each other, I don't mind going with 'burst',
Knowing the word can be insufficient to capture the massive release of energy in the "Explosion".
bear