This question is silly because difficulty could differ so much between departments, between faculty, and between different classes in the same college, much less across colleges.
And Student A may find learning a breeze with one subject/faculty/department combo but difficult with another while for Student B, it’s vice versa.
Now if you compare specific subject classes, (such as operating systems), you can at least compare the difficulty and depth of the finals.
But I don’t understand the point of this question anyway. What is the motive? All of the Ivies/equivalents will have mostly challenging classes but some easy ones (other than maybe Caltech, Oxbridge, and perhaps MIT).