Eli5: What’s the difference between explosion and combustion?

Question

I think I’m being stupid or overthinking this, but if for example, you’re burning in a controlled manner, a bottle of propane in a burner producing a slow burning flame, and then you ignite the entire bottle causing it to explode, are these both examples of combustion? Is an explosion just really really rapid combustion? If so, where is the line drawn between these terms and how is the chemistry different? Or have I misunderstood these terms?

In: 5

Answer 1

These are the levels of hierarchy all based off how fast the reaction of chemical into kinetic energy is (some even come with a shockwave):

1. Detonation – aka primary explosive, very powerful and very fast shockwave
2. Explosion – secondary explosive, fast shockwave
3. Deflagration – very, very fast burn, small, barely noticeable shockwave
4. Combustion – very fast burn, no shockwave
5. Burn – A well-done steak or above.