The obvious difference is class size, and in one way or another it is the thing that Butler flaunts all over its website as the reason to go there.
This shows up in the numbers such as an 11:1 student:faculty ratio vs the 18:1 student:faculty ratio of instate flagship, IU. It also shows up in the fact that only 3 of 1100 classes have over 100 students while 300 of 4400 classes at IU are over 100. At the other end of the spectrum, 560 of 1100 classes at Butler, or about half, have fewer than 20 students. At IU, small classes under 20 number about 1500 out of 4400, or about a third.