a latte is typically prepared with approximately one third espresso and two-thirds steamed milk, with a layer of foamed milk approximately 5 mm (188; inch) thick on the top.
A flat white is generally made with an 8531; espresso and 8532; steamed milk.
答案是他们的奶量几乎是一样多的，latte多了一层泡沫奶，所以小胜~~
以上摘自wiki~~
http://en.wikipedia.org/wiki/Latte
http://en.wikipedia.org/wiki/Flat_white