Cacao Vs. Cocoa

Updating Your Chocolate Vocabulary Cacao? What is that? Don’t you mean cocoa? And how do you say it anyway? Chocolate linguistics can be confusing. It comes down to this:
The official name of the chocolate tree is Theobroma cacao but, some experts say, over the years the word “cacao” became Anglicized, and probably through error, people started replacing it with the word “cocoa”. (Most of us grew up saying cocoa bean, not cacao bean.)
Now, with the rebirth of old-style, artisanal chocolate there is a movement to reclaim the bean’s rightful name: cacao (pronounced Ka-Kow).

The Difference
Cacao: pronounced Ka-Kow. Refers to the tree, its pods and the beans inside.
Cocoa: pronounced Koh-Koh. Refers to two by-products of the cacao bean – cocoa powder and cocoa butter. Both are extracted from the bean when it is processed in the factory.

Understanding The Label
Often you will see packages labeled now with "% cacao." What that refers to is the percentage of cacao bean solids present in the bar. There is an inverse relationship between the percentage of cacao in a bar and the amount of sugar. So:
• A 75% cacao bar has 25% sugar. • A 65% cacao bar has 35% sugar. • The higher the % cacao, the less sweet the bar and the stronger the chocolate taste.

(c/p from http://www.allchocolate.com/)