The generated voltage potential is going to be across the battery terminals so you are basically DC quick charging the battery. There are losses in each of those processes, so it is not 1:1. You have conversion loss in the power inverter, chemical losses in the battery, etc.I am having a not so fun time trying to search it out on the forum so apologies as it has to have been answered before.
When braking you get to see how much power is regenerated. I wanted to understand just how high that number can be before it exceeds the systems ability to absorb it and does it absorb it on a 1:1? Is it a wholly separate system from the 3.3 charger?
The AC charger is separate and converts 120/240V to DC to charge the battery.
Whenever you have an electric vehicle, the designer has the option to have a charger internal and/or external to the car, the internal charger for the Volt is the 3.3kw charger you mention. Vehicles with DC chargers basically bring the battery terminals externally so that it can be charged via an external charger (Low or even no cost option in most cars). This is why regen is disabled when the battery is fully charged, this is more noticeable on the Bolt EV since it can actually charge to full, whereas the Volt doesn't ever charge to full with the AC charger.