The G3 is a proper abrasive polish, so will physically remove the scratch (or at least lessen them if they're a bit too deep to fully remove) by cutting back the surrounding paint/clearcoat level with the bottom of the scratch. Scratches that are too deep to fully remove will have their edges rounded making them less noticeable thanks to the way the light now reflects off of them.

I'm not sure how oily the G3 is so unless you use a panel wipe style cleansing product after you may get some drop back making the scratches a little more visible than at first seemed, but still substantially lessened.

Using the AIO polish afterwards will fill the remaining scratch, but expect that to drop back over time leaving it looking as it did after the G3 stage, but still a big improvement over just using the AIO on its own.