This is what profoundly gifted means to me. And it shows up in his vocab and information scores. S2 is bright. Great student. But there is nothing like this insatiable hunger in him. He does what is expected of him very well. S1 is driven by an internal burning fire. All I do is leave lots of dry wood around (in the form of books) but the fire does the consuming.
Not intending to pull this thread off track or give you anything additional to add to your already very full parenting plate, but fwiw, I wouldn't make any assumptions that S2 is any less gifted than S1 based on the lack of seeing that intense all-consuming insatiable hunger for knowledge. While this characterizes some highly gifted children, it doesn't characterize all highly gifted children. Unless you've had your S2's ability tested and know for certain otherwise, I wouldn't automatically make the assumption that he's any less gifted, just a different personality.
Best wishes,
polarbear
