They in fact differ wildly between students and between colleges! UIC and NIU are commuter universities where students generally don't live on campus. Students at UIUC live in campus-provided housing for their first year, but not generally for subsequent years. Everybody, whether they're in school or not, pays for housing. So no, the cost comparison you're offering here is not very useful.

Shortly later

I also think you might have to ask around to find a student paying full price for books.