If you have the generator transfer switch option, then there will be an automatic (or manual) transfer switch that essentially does the same thing as unplugging from the shorepower pedestal and plugging into the generator.
If an automatic transfer switch, when it senses generator power and lack of shorepower power (or some combination thereof) it will automatically switch the RV to the generator.
If a manual transfer switch, you must flip the transfer switch to the generator or shorepower power - depending on what you desire the source of power to be.
And while not shown on the drawing, there will be a safety provision to prevent generator power from appearing on the RV's main power cable.