“So does that mean Purdue uses a completely seperate admissions pool and process for internationals?”
Not necessarily, it only means that they report stats differently. Most schools, even public institutions, want to build a well rounded, diverse student body. They want international students, especially those that can contribute in unique ways to the college experience of other students (and let’s be honest, to pay more tuition also).
Purdue being a public state university though has a mandate to be there for Indiana residents first and foremost.