Some "big time" professors...you know the ones that write the books used universally are at these top schools because of research funding...they get more money...you get more exposure to the best of the best...better money = better equipment. Also LOrs coming from these guys from top schools, who get lots of research and usually set the trend for innovative work carries a little more weight when applying for residency.
@ Vanderbilt every anatomy table has its own big screen tv with high tech interactive tools.
Wash U just has enough money to set their students up with almost anything they need.(facilities, exposure, etc) Also Wash U gets big grants for their students too, so it's easy for them to ship them around the country and even the world for lots of types of research.
Not to mention these top schools also have big time financial aid packages they can award. I think at Wash U they don't allow anyone to accept over 20K in loans per year.
I mean, up to a certain point it doesn't matter for medical students, but there is a big gap between top 20, and bottom 20.
If it's pure medical knowledge you are after, then IMO i don't think it makes much of a difference. But for all the other stuff you could use to beef up your resume/lifestyle/etc it makes a difference.