What's the distinction between ice wine and late-harvest wine?

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Dear Dr. Vinny,
My wife and I have become very fond of ice wines. The wines I find labeled as ice wines are generally Vidal or Riesling. But lately I've tried some wine from other grapes such as Chardonnay and Zinfandel that were labeled as "late harvest." What is the distinction between ice wine and late harvest?
—Scott M., Prescott, Ariz.
Dear Scott,
The short answer is that all ice wines are also late-harvest wines, but not all late-harvest wines are also ice wines. Both ice wines and late-harvest wines are made in a very sweet style. Late-harvest wines are made from grapes left on the vine longer than usual, allowing them to get riper and riper. This makes the grapes naturally dehydrate, concentrating their flavors as they take on sweet, raisin-like qualities.
Ice wine is a type of late-harvest wine that's made from grapes that are left on the vine so far past the typical growing season, they actually froze before they were picked. Because the water inside the grapes freezes—while sugar and other solids do not—the result is an even more highly concentrated and sweet wine. (There are also "icebox" or "iced" wines made from grapes that are picked and then frozen mechanically.)
—Dr. Vinny