Cross-plane vs flat-plane V8
Both engines fire every 90 degrees. Add the banks together and they are the same. The difference is what each bank's exhaust gets.
Cross-plane: uneven per bank
A cross-plane crank has its pins at 90 degrees to each other. It balances well, but the firing order jumps between banks unevenly. Each bank sees gaps of 180, 270, 180, 90 degrees. Two pulses arrive close together, then a long wait. Do that on two pipes and you get the lumpy V8 burble.
Flat-plane: even per bank
A flat-plane crank puts all the pins in one plane, like two inline-4s sharing a crank. Firing strictly alternates banks, so each bank sees 180, 180, 180, 180 degrees. Steady pulses, no lope, and a hard, high note. The trade-off is more vibration, because the second-order shake of an inline-4 is back.
Hear both
Big Cross is one of the three free engines. Flat Crank Eight is in Pro. In the builder you can also take a cross-plane V8, switch it to one pipe, and listen to most of the burble go away, which shows it was never about the cylinder count.