NW and U of C are both great programs, but are very different and cater to different people. In terms of their children's hospitals, NW is a larger, more academic program in terms of the culture within the hospital. I felt fellows have a very strong role within the hospital at NW, more than that at U of C. This can be good or bad depending on how you look it. On one hand, the fellows are usually pretty bright and offer a more intimate learning environment since they have more time than the attendings to sit and teach. Also, the presence of a fellowship program usually indicates an active division that has high patient volume and thus more exposure for residents to that subspecialty. On the other hand, residents have less autonomy with the presence of fellows. This is true everywhere, despite how many programs insist they are "not fellow run" and that their "fellows do not manage the patients." This is total BS from any program that tells you this. If the fellows are not managing patients, then how are they learning? They are in training. They are not attendings.
Both hospitals have good exposure to medical subspecialties, but NW sees a higher volume based on the larger size of the hospital. The surgical subspecialty presence at NW is huge, much more than U of C, with the exception of neurosurgery. This provides a unique experience to NW residents in the management of surgical patients. You get adequate exposure to surgical patients at U of C as well, but not at the volume of NW. However, general peds exposure at NW is not as strong. The majority of the NW residents that go into "general pediatrics" seek jobs as hospitalists in a large medical center, rather than primary care community pediatrics. U of C has a stronger focus on community based pediatrics, while maintaining a good balance between primary care and subspecialty exposure. Also, something that U of C has that is extremely unique is their rotation at La Rabida, which is a hospital for children with chronic diseases on Chicago's south shore. As a second year, you pretty much run the hospital, which is an extremely challenging experience. You have a role similar to the NW residents who rotate at Evanston, but the patients at La Rabida are much more challenging, such as kids with chronic lung disease and trachs, sicklers, diabetics, CP, rheum kids, etc.
Despite the size and culture of NW, it is not as strong in terms of their research power in comparison to several other programs of similar size and reputation. I think currently they are actually pretty similar in the amount of research they do. However, this may change as NW s looking to move the children's hospital to the main medical campus to have better access to the research facilities there. But U of C is also making strides with recruitment of basic and clinical scientists and the expansion of current research facilities that are dedicated strictly to children. Both residencies have a research requirement, although it seems more organized at U of C as they have a curriculum dedicated to your research project and keep you on task having you do a little bit over the entire 3 years. At NW it seems that the research project is more of a third year project.
The residency programs are organized differently according to their call schedules and benefits. NW kills you the first year and rewards you later. I think they have something like 11 months Q4, then 7 months Q4, then 5 months Q4 over the 3 years. U of C is pretty much equal over the 3 years, I think around 6 months each year. NW doesn't provide food to their residents on a daily basis but gives a food allowance for call days, while U of C provides breakfast and lunch daily and money for dinner on call days. Parking is half the price at U of C but less accessible by public transportation. Because of the neighborhoods, more NW residents are able to live within walking to the distance to the hospital, but you will pay for it based on the cost of living of the neighborhood. However, a nice thing about the U of C location is that it is easily accessible by car from anywhere in the city, including the suburbs for those with families. It is almost impossible to live in the suburbs and commute to NW. This probably is not a factor for the vast majority of applicants.
All in all both are very good programs with a unique culture that you will have to assess when interviewing. If you are really interested in both programs and are confident that they will both be ranked among your top programs as I was, I would recommend rotating at both because programs can always put on a show for one day during the interview. Impossible to do that for an entire month. Reputation is still better at NW. In fact, many of the residents at U of C hadnt heard anything about U of C Children's Hospital when they applied. Obviously they knew of the reputation of the medical school. Many applied only because they thought Chicago was a cool city and they were applying to NW anyways and it would be nice to see other programs in the city. They were impressed during the interview day and chose U of C over NW. If I could summarize the key difference in one sentence it would be...NW will prepare you phenomenally for practice in a tertiary care environment and academic medicine, while U of C will prepare you well for virtually any path of medicine you choose.