Wirbelwind: 2cm-Vierling 38, muzzle velocity 900 m/s
Ostwind 3,7cm Flak 43, muzzle velocity 820 m/s
The Ostwind shell is much heavier, so it should retain it's speed for a longer time. But I don't have more accurate ballistical data right now.
But of course you can check bullet drop at various range offline using the .target command.