tl;dr The former is much harder than the latter.

With the first couple of exams of M1 year under my belt, I can safely say that UChicago biochem makes med school biochem look like a cakewalk. Sure, med school is hard and the information flows like a firehose, but at least we don't have to learn the intimate details of every step of a pathway. No structures or arrow-pushing either.

P.S. If you have to take biochem at UChicago, take it during the summer. It's easier and the instructor is much better.