As far as I know all Proofgrade settings are simply presets for the manual options. When you have something configured to use a Proofgrade setting you can switch it to manual settings and the fields will be populated with settings corresponding to the previously-selected Proofgrade option.
For example, if I have something set to 3D Engrave on Proofgrade Medium Basswood Hardwood:
And then I switch it from Proofgrade to Manual:
I end up with these manual settings:
Note that if I had any other Proofgrade option selected (Photo, Graphic, etc.) then I’d end up with different manual settings when following these steps.
As far as I can tell there’s no difference between using the Proofgrade settings and the equivalent manual settings.