I doubt my own opinions on genius will have much credibility given I’m not not one. But studying geniuses it seems to me that developing an intuition for the subject is what truly sets them apart. Einstein had the impact he did because somehow he knew what areas to work on. In the sea of confusion and subjects floating around at the time he zeroed in on Brownian motion, Relativity, Photoelectric effect and Lasers. Any one of these is enough to go down in history as one of the greats.
I have a friend who’s extremely intelligent. What I’m often surprised by is the speed of thinking. It seems way too quick to be the result of any rational deliberation. Kind of reminds of the policy and value networks in alpha go. Their brains are wired to search much more effectively through the search space.
The other aspect is meta cognition. They understand their own abilities and how they improve . Which means they are able to train themselves with an efficiency we cannot.