UNC-Chapel Hill is ranked #7 and UT- Austin is ranked #5 for undergraduate business. There is no appreciable difference.
Of course, this is a matter for your family to decide. I would assume that the university your sibling attends would not make a difference in the BS financial aid. BS decisions won’t be due until after your sibling gets their university acceptances, so there will be time for your parents to make a cost-benefit analysis.