Hammer. Listen.
When you go to the shop, there are 3 kinds of sugar you can bu: white, brown and raw.
What is labelled as brown sugar is simply white sugar with molasses added to it.
WHITE SUGAR (ALSO CALLED TABLE SUGAR)
Pure sucrose naturally found in many fruits and vegetables. In nature, it can be found in either sugar cane or sugar beets, but by the time it has been refined to a white crystal, the two are chemically identical.
RAW SUGAR
To make sugar, machines are used: sugar cane (or sugar beet) is initially pressed and the juice is then mixed with lime to achieve the desired ph balance and to help settle out impurities. Reduction of this solution through evaporation produces a solid mass that is passed through centrifuge to get sugar crystals. It is then dried further to produce granules. This sugar is light brown in color and is termed raw sugar. The brown color of raw sugar is due to presence of molasses. Raw sugar is the most natural sugar you can hope to lay your hands on.
BROWN SUGAR
Do not confuse raw sugar with brown sugar. Brown sugar is simply refined white sugar with a molasses syrup mixed in, then dried again.
http://www.mslimalicious.com/2012/04/white-raw-brown-sugar-what-are.html