What Is the Difference Between Molasses and Treacle?

In the United Kingdom and Europe, molasses is often called black treacle. Originally, treacle was a pale, refined type of molasses that was notably sweeter and had a more mellow flavor than most molasses. Treacle can be substituted for molasses in most recipes, but molasses usually doesn't work as a substitute for treacle, unless it is a very light and unsulphured molasses. Other varieties of molasses include blackstrap, light, medium, dark and sorghum molasses.