following video demonstrates the difference, the teacher ignites the pringle can (contains hydrogen), as the hydrogen partially burns up, air enters and the mixture crosses down into the UEL, thus allowing an explosion (detonation wave) to occur.
I used to prank my house mates similar way back at university. I would use a large milo or coffee can, with some small holes at base and a central hole in the lid. Fill can with natural gas from stove. Ignite can lid central hole, it will burn like a candle. place on floor and walk away.
while the flame is visible, there is no explosion, just combustion. after around 1/2 hour (depending on size of can and size of holes etc) the flame has diminished in size until it is basically invisible. be nervous. booom, can explodes, lid hits ceiling, detonation has occurred, non engineering house mates are in state of mild shock.
ahh good times, nothing like a bit of local detonation to liven up a movie.
My high school chemistry teacher did that, with a coffee can. I gather that when he's done it in the past, the lid did not smash through a fluorescent light fixture like it did for us...