btw, are you comparing the program within the same level? I remembered the old time, I stayed up until 2 or 3am to work on my engineering degree. many of my classmates stayed up whole night. and that happens at least 2 nights a week. my friend in UIUC is even worse, he stayed up three nights every week to work on projects.
I have not heard anybody working late this frequently in MBA.
and btw, I agree that undergraduate is harder than master program in USA