Purdue and IU have almost identical enrollments and admission standards. Average SAT score for a Purdue student is 1280 and Indiana 1246. Purdue has a much lesser acceptance rate because of their engineering school. Purdue received almost 20k more applications than Indiana did for the fall of 2018 and I'm guessing the majority of those were for kids applying in hopes to get into the engineering school.
It is a comparison, your right, but the name brand, flagship public university of the state shouldn't (at least in my opinion) have a nearly equal ratio between in-state/out of state students. It wasn't ever that way until about 10-15 years ago. IU is not only deferring, but outright rejecting in-state kids in favor of out of state kids. That's why Indiana's acceptance rate is so high right now, they're willing to take as many out of state kids as possible for $$$.