Ggglygy-snip-
The environment you are in is a huge difference, like University of Chicago's Grad school(booth) is one of the top business schools in the world, the students in there are all extremely brilliant, professors treat them differently compared to a school like University of Illinois. You'll get a better eduaction because most the teachers are actually Involved with real world macro economics, and the teachers actually care about helping students ALOT(mostly because the students most likely will be hired into some prestigious job).
There's other things like the people that are around, you, and how much they pressure you etc etc. I can't speak for Harvard, but at least from my own experience there are hardly any "top schools" that have stupid people in them(lazy is one thing, but actually lacking intelligence is another)
EDIT: Also net working, if you gather the greatest minds in your country into one school, and they start to form their little cliques you'll get at least a few very beneficial frienships.