Tatum is slightly better than Brown. If Jaylen learn how to dribble him and Tatum will be on same level. Jaylen inability to dribble is the only thing holding him back. If Brown learn how to dribble he would also become a better passer and will live at the free throw line because he blows by people even though he got bad handles. IF Jaylen learn how to dribble he has a chance to be a top 15 player in in NBA.
Offensive wise Tatum is a better ball handler, passer, better free throw shooter and slightly better rebounder. They are both similar 3 point shooters. However I think Brown is a slightly better defender, a better finisher at the rim, have a better mid-range game, and is quicker.