In two different positions, A and B, I placed the same firework at the same time. However, the two initial ascending stars don’t rise to exactly the same height, even though the two explosions are synchronized in time.
Why don’t the two ascending stars rise to the same height?
by default, FWsim simulates the inaccuracies inherent in real fireworks. If you want to change that, simply click Tools → Preferences. Under “Simulation”, you can configure:
Realistic: random variations are added to heights and timings. This is the default.