I don't have any research results to cite, but I can tell you what I have observed both in shcool and in the workplace.
First thing that can distiguish between two people of roughly the same brain power, skill level, background and knowledge is attitude. There are people who are always smart asses and people who go the extra mile and people who have to be sat on to accomplish anything. They get different results.
The next thing is personality differences in particular how they relate individually to professors or supervisors. I might do really well at one institution because the professors there have compatible personality types to mine and fail completely somewhere else because the personality differences are too great. Many organizations tend to favor extroverts, for instance, which put introverts at an immediate disadvantage. Or a very rules-based professor may not care for the brilliant but freewheeling student and give him worse grades than the plodder who always follows the rules exactly. This could easily be reversed in a different instititution with different personalities.
The final distiguishing factor is the skill at playing the political game. All organizations that have more than one person have office politicsa and that includes academia. The person who plays the game best will tend to have the best results if all other factors are equal and often even when they are not. There is no excuse for not learning how to play office politics well. That would be like trying to be a prize fighter and tyoing one arm behind your back. It will put you at a severe disadvantage through your entire academic and porfessional career.