If all those engines had the exact same displacement, only major difference in those turbos outputs would be
heat. There is a notion of efficiency of a turbo - a 100% efficient turbo would only add as much heat to the air as the absolute minimum that thermodynamics requires. A 50% efficient turbo would add twice that heat to the air.
Different sized and shaped turbos are most efficient at different psi and flow numbers. A small turbo may be able to push a large psi and cfm, but it will be less efficient there, and put a lot more heat into the air than a big turbo at that exact same psi and cfm. This is why it's important to size a turbo appropriately from the compressor map. The idea is to try to stay near peak efficiency as much as possible.
The cooler air has a greater density, allowing you to add more fuel and get more power. The cooler air also keeps the engine away from dangerous detonation, allowing one to advance ignition timing and maybe the IVC point, also resulting in more peak power.
