No, they are not. Molasses is the syrup left over after sugar has been refined and crystallized from sugar cane. It is sold in several grades, from sweet and refined 'first' or light molasses, to thick, dark and slightly bitter blackstrap molasses. Treacle is a form of molasses, one that has been blended to produce a sweeter syrup which is less prone to becoming gritty. Golden syrup, which is sweeter than treacle, is made from refined white sugar.
Molasses has a dominating taste that gives a powerful flavor to sticky, moist cakes: gingerbread and fruit cakes are probably the best known. It is also used for making toffee and fudge, and its slightly bitter taste can enhance savory dishes such as pork and dried bean casseroles, gravies and American-style barbecue sauces. Golden syrup is used as a sweetener in baking, or as a topping for ice cream or steamed puddings.