In some Japanese universities, there are "insider" and "outsider" undergrads. The "insider" ones are those who come from feeder or affiliated high schools and given the chance to apply directly. The "outsiders" are those who take the general national exam then apply to their university of choice. Touma and Barato seem to be "insiders", especially given their training in high school. Chinatsu came from Honshu, so she's definitely an "outsider". Entrance exam results and rankings are given separately for insiders and outsiders because, while the actual exams are exactly the same, they are administered through different systems. Chinatsu seems to be the top scorer among outsiders but Barato is the top scorer overall. She just didn't realize it because she was on a different ranking table.