IMO just too soon to extract much from comparing their OPS. Alot of the reason Cozarts isn't higher has to do with contact ability, he's not gobbling up the singles. I think it's a mistake not to expect him to continue to progress and potentially be an above average hitter, plus defense and base stealing he's far more than just "safe". And while Hamilton could be an even better defender and base stealer in pretty short order he still could have issues with the bat in all aspects, contact, power and discipline. If so he's potentially a non prospect. In a year or 2 I might come to a point where I can see that bat is gonna not be a drag on the rest of his game but until that point I will pull back the reigns a bit on him.
Cozart may be safe and Hamilton could be a star but IMO it's just to soon to call either of them those things and those things alone.