deflagration

...from say a propane leak. You can't exit the house prior to the explosion but you do have a bathtub full of water and a bunch of mattresses on the other side of the building. Would it be better to seek refuge in the tub of water or behind the mattresses? This question comes from a long debate...

What's the difference between the two? I know one is slower (deflagration), and the other rapid (detonation), but where is the dividing line? One definition I've heard is that detonation means the speed of the flame-front is supersonic, but others say that this isn't so. Does deflagration...