Let's try a different tack....
Pre-ignition is generally caused by hot spots. So, let's say we have a piece of carbon buildup where the edges start to curl up. Can be a piston, valve... whatever. This piece of carbon can get hot enough where it starts to glow... in effect turning itself into a glow plug. This can cause the fuel/air mix to ignite. It generally (not always) occurs prior to spark plug ignition.... which is why we call it "pre-ignition." Everyone clear? Moving on.....
Let's look at what happens after pre-ignition...
Pre-ignition will ignite the F/A mix. This can cause either a normal or abnormal combustion event. In the normal one, we get a slow burning (relative) flame front that propagates throughout the cylinder exactly as you would a spark plug initiated event. Since it happens early, that cylinder will tend to run hot, but it's still a normal... slow burning flame. This running hot can (not always) lead to detonation.... which is an explosion of the mixture instead of a slow burn... an abnormal event... and the one that's dangerous.
So, pre-ignition "can" lead to detonation, but the two are still different, independent events.... detonation can occur without pre-ignition.... with lean mixtures and too much ignition advance being the prime culprits.... not pre-ignition.