Spark knock and detonation have different causes but they end in the same result: a very sudden combustion and resulting shock wave, so I think in general they sound about the same.
What may make a difference is where in the combustion chamber the sudden burn occurs.
With spark knock it generally happens in the last bit of unburned fuel/air mix far from the spark plug.
But with a hot carbon deposit or hot spot on on an exhaust valve etc. it could happen elsewhere.
Think of tapping a cymbal in different places with a drum stick.
Regarding different engines the size and shape of the pistons and other parts will give different resonant frequencies.
Regarding E85, just say no.
With just the right (wrong) amount of lean-ness combustion temps soar and hot spots can promote ping.
You can also burn out exhaust valves.