The difference between unsulphured and sulphured molasses is that sulphur dioxide is added to some batches of molasses. Sulphured molasses usually comes from young sugar cane. Though sulphuring prevents fermentation, the molasses is less sweet and is used less often in recipes than other types of molasses.
Some believe that the taste of unsulphured molasses is "cleaner" overall as well as being sweeter.
Molasses is the liquid that is left over when sugar is processed. There are several kinds of molasses other than sulphured and unsulphured. Fancy molasses is a very light and sweet molasses from the first boiling of the sugar cane or sugar beet. Light molasses is also produced from the first boiling. Both are sweet enough to use as toppings for breakfast foods such as pancakes and oatmeal.
Dark molasses comes from the second boiling of the beet or the sugar cane. As its name implies, it is darker. It's also thicker and tastes less sweet than light molasses. Because of this, it's used in more robust types of desserts such as gingerbread and molasses cookies.
Blackstrap molasses is the darkest and thickest of the types of molasses. It is bitter and has a spicy flavor. It is rich in vitamins and minerals, including such essentials as iron, copper, calcium, magnesium and potassium.