As I mentioned, I dug these numbers up a while ago. I seem to recall that the numbers were different depending on the source. For example, I apparently found a different source which listed the 100 largest colleges based on the number full time undergrads. Here's how the Big Ten and ACC schools stacked up on that list.
If these are correct, it appears that Rutgers has a disproportionate number of part time students compared to the other schools.
Rank College FT Undergrad 3 Ohio State University 41,117 4 Penn State 39,520 9 Michigan State University 35,645 10 Rutgers University 33,392 11 University of Illinois at Urbana-Champaign 31,989 12 Indiana University - Bloomington 31,728 17 University of Minnesota - Twin Cities 29,168 18 University of California - Los Angeles 29,004 21 Purdue University 28,682 22 University of Wisconsin 28,555 29 University of Michigan - Ann Arbor 27,258 39 University of Maryland - College Park 25,410 69 University of Iowa 19,911 78 University of Nebraska - Lincoln 18,817 91 University of Southern California 18,208 16 Florida State University 29,185 45 Virginia Tech 24,841 58 North Carolina State University 21,023 97 University of Pittsburgh 17,887 100 University of North Carolina at Chapel Hill 17,645