Umm, the Downstate figures there include an 8K+ "miscellaneous" amount. You don't pay that to Downstate, they're just estimating random money you'll end up spending for whatever you feel like.
The Mount Sinai #'s you're quoting don't have that # thrown in there, so if you want a fair comparison you should include a miscellaneous charge too, or drop it from the Downstate figure. Keep in mind that the miscellaneous charge includes Downstate's health insurance estimate, so you should at least keep that portion in.
Downstate comes to $40395 if you strip the miscellaneous charges down to just the health insurance charge that Mount Sinai's includes.
And umm, nobody ever said the total difference would be INSANE or anything, lol. It's cheaper, but it's not supremely insanely cheaper.
Also, comparing Downstate to a much more highly ranked school doesn't really make that much sense, lol. If you compare Downstate to say, NYMC, you'll see that the savings makes a lot more sense, since not only is NYMC more expensive than Mount Sinai, it's not neccessarily a better school.
I'll be honest too, if I got into Mount Sinai I'd pay the extra $11K a year, lol.