Illinois is ranked 33rd nationally (9th for publics). Ohio State 41st (15th for publics).
Illinois has a selectivity rate of 44%, Ohio State 51%.
Illinois average SAT 1410. Ohio State 1400.
Illinois average ACT 32. Ohio State 31.
Illinois obviously is well known for their engineering and science programs, which are all highly ranked. Ohio State doesn't necessarily have that one area it's most known for, but is well ranked across a wide variety of degree programs--top 20 in engineering, business, social sciences, nursing, chemistry, public affairs, etc. You can pick virtually any area of study and you won't have to scroll too far down the list before you find OSU.
I say this not to say that Ohio State is better than Illinois, nor the opposite. Just that your notion that Ohio State is an easy school to get into for the average student is outdated.
Ohio State has some professional athletes on campus playing football. It is what it is. Most of those guys aren't really students.