It should be the same as if you put an electric fan on a rad and ran it with the generator. In theory.
Nope. The electric fan should be more efficient because it would not be running continuously - provided one fitted a thermo-switch. That is why all (or nearly all) cars are fitted that way oem.
There were other considerations in the case of cars, like the fan will pull much more power at high engine revs (fan-speed/power cubed relationship) and probably most of that time while the engine least needed extra cooling (above the draught caused by the forward motion) and weight consideration - less metal in the rad and less coolant in the system and the warm-up times for reducing high engine-wear periods. There would be others too - streamlining, aethsetics, cost, etc.
Not so much difference if running 24/7 and radiator is vertical but other airflow options could improve the efficiency. Still generally a pumped system with a rad, so the pump will be absorbing power all the time and will be the bigger energy user.
On my 1960/70s Fords, I always fitted my larger pump pulley to decrease the energy requirement as the oem was always well over-sized.
Regards, RAB