Molasses is simply the result of a syrup (usually thick, but can be light in content) produced from sugar cane into actual sugar. I remember eating cookies with molasses in them and appreciating them for their unique flavor and aura. If you watch the movie Willy Wonka and the Chocolate Factory, you will see a machine smashing what is suppose to be sugar cane. Willy Wonka (aka Gene Wilder) mentions that the juice is extracted through the machine and turned into molasses. Although the molasses looked light, it was rather dark on the edge, towards the bottom. That is what is known as "blackstrap" molasses.
The main difference is age. Maturing plays a huge role in categorizing molasses. Although processing plays an extensive role, that is the result of the maturing of the sugar cane itself. Blackstrap molasses is like tar, in comparison to regular molasses because blackstrap molasses is the final result of sugar refining, which makes it extremely strong. The sugar cane used in blackstrap is rather matured, whereas it's young or mid aged when used in regular molasses. Regular molasses is part of the sugar refining process, hence why it isn't as strong. It is also thicker in content and richer in flavor, as opposed to regular molasses. It is very sweet, but also bitter in flavor. As it's darker in color compared to regular molasses, the color clearly gives away it's difference. In fact, if you use blackstrap as a regular molasses or with recipes that require using regular molasses, it will ruin the recipe.
Blackstrap molasses is not really common to the average grocery shopper, therefore it isn't always found in a regular grocery store, but is sometimes. Blackstrap molasses is very popular to health fanatics. Why? According to statistics of molasses there is 40% less sugar rate than regular molasses. In fact, according to health experts, blackstrap molasses provides vitamin D, as well as elements such as magnesium, potassium and iron. Because of this, health fanatics are attracted to blackstrap molasses on a variety of wavelengths.
Although you can make regular molasses right in your kitchen, at home, it is not recommended. You can do this by using several different sugars and extracts, which when combined make a flavorful molasses as a result. The sugars are about 40% higher than blackstrap molasses so it's sweeter in taste, but also lighter, as a result. Attempting to make blackstrap molasses is risky, as it can be toxic due to it's "tarrish" content and strong overtones.
Although, skeptics believe molasses is the same, it is clearly different which studies have proven. Everything has its differences, including sugars, ingredients, and molasses.