Teaching style, type of assignments, grading style . . . impossible to generalize about an entire university. It’s not like a high school, where teachers are required to give certain types of assignments and grade a certain way.
They are both excellent schools. I think Penn has a bit more of a “preprofessional” atmosphere, given that they have Wharton and a nursing school. My sense – just a sense – is that Cornell has a wider variety of students. Also, Penn is huge on legacy admissions, so you’ll meet a lot of second and third-generation students. Another hunch is that Penn’s student body is on average wealthier.
In the final analysis, it really does not matter. Go to the accepted student days and just make a choice based on your gut.