Alain67 1527 post said IMO a spectral analyis would show the difference.
Right on- consider a major difference
An explosion makes as major increase in a positive pressure ( simplified as blowing into a ballon to inflate it )- and then followed by a decrease in pressure. As pressure decreases, sound intensity decreases- probably with little echo- Sound **speed** is a function of temperature not pressure. rapid decompression lowers temperature.
A decompression makes a major decrease in pressure.
Now both can sound the same to the ear- but any spectral analysis from several mikes should be able to immediately determine which happens first