It seems the Academic Achievement Test and the CSAT were completely different exams

I know someone who had a case like this...
Took the Academic Achievement Test in their senior year of high school
But took the CSAT while retaking the exams
They got into Pusan National University, attended for a month, and then immediately started studying to retake the exams...
And eventually went to Sogang University...
Even though Pusan National University was quite prestigious back in those days...
Moving from Pusan National to Sogang seems like a huge jump;