For me medical school was much harder than residency. The book learning was tedious. When I started clinical rotations in 3rd year, I felt like a fish out of water.
Residency was physically hard and emotionally challenging. But like all residents, I found myself on the very steep part of the learning curve during the 1st and 2nd years and it was exhilarating to become really good at something that I wanted to do. I made lifelong friends and everything I did during residency (and later fellowship) became the keystone for becoming the doctor that I became.
I did my residency during the era before hour restrictions. I had fun and tremendous satisfaction and I would do it again.
David Chan, MD from UCLA, Stanford Oncology Fellowship
Source: Quora Digest
For me medical school was much harder than residency.