Tell all of us about the difference between and explosion and deflagration ...
With pleasure. A deflagration is a type of explosion.
Take it up with an Astrophysicist, Scott Manley ... Explosion vs Deflagration. There is a difference.
An excellent video by Scott Manley. Funny how it does not discuss explosion v deflagration, but it does discuss detonation vs deflagration. Let's park that thought..
On the other hand, an explosion is most often experiencing supersonic front speeds and the huge overpressure resulting from that Detonations that are moving at supersonic speeds.
Well, "most often" does not mean "always". But hey, common mistake. But here's the important thing: you are now getting the words "explosion" and "detonation" extremely muddled. And the reason probably relates to another term which we haven't yet covered: "high explosives".
Let's expand on that. If you want to buy an explosive, you probably want a "high explosive". These explosives are everyone's favorite: they are particularly destructive, they do indeed detonate supersonically, and by "everyone" I mean miners, demolishers, the Army and MythBusters. But those are not the only kinds of explosives. There are two other types: "low explosives", that deflagrate subsonically; and, things that explode for some other reason. This very last type is absolutely not marketed as an explosive, because it is much too accidental and boring, such as a COPV tank in the Starship upper stage that contains no combustible fuel, but instead contains something like oxygen or nitrogen. (And "boring" might be the wrong word, depending on the circumstances, e.g. if there is a tank of methane nearby.)
Which brings us back to GGGP which said: Something in the upper section ... exploded without igniting.
So, getting back to pedantry. If we were to be pedantic, we would not quote you. Instead, we might expand on the GGGP post and say: "Something in the upper section exploded without igniting, combusting, deflagrating or detonating. And that thing did not deflagrate, detonate, combust or ignite." It exploded (meaning that stuff went everywhere) without igniting (or any of the other things.)
It sure is a tough job being a pedant. You have a nice day.