I hate to sound like an idiot, but after making myself an evening "coffee drink", I decided it was time to hit the Internet Ouija Board and figure out whether I made myself a cappuccino or latte. Turns out it was neither -- I use proportions that are pleasing to me and that's all that really counts, isn't it.
But I was surprised by the number of people who are not only interested in this subject, but terribly confused by the definitions. From Coffee Geek:
Cappuccino: The undeniable classic and darling of the espresso world. It is the perfect example of milk and coffee done right. The cup itself should hold 5 to 7oz and no more. Sharing the space in the cup in one-third proportions is one shot of espresso, one-third steamed milk, topped by one-third foam.
Latte: This is a wildly popular drink in North America. Large quantity of milk, small quantity of coffee. Something the Italians might serve to their children.
If you just Google for cappuccino vs. latte, you'll find numerous blogs where people don't understand how you can make a drink of thirds in a 5-7 oz cup with a single shot and end up with a full cup of coffee.
So consider this: take a classic cappuccino cup (which is much smaller at the bottom than it is at the rim) and dump in a single shot. What you have is a cup that's 1/3 full by height -- not by volume. If that's an inch of coffee, then add an inch of steamed milk and top it off with an inch of foam.
Makes perfect sense to me.
* Coffee Geek