What Is The Difference Between Treacle, Molasses And Golden Syrup?

Treacle or black treacle and molasses as it is know in the USA are essentially the same thing. It is the syrup obtained at a stage of extraction from raw sugar cane. The dark syrup left at the end of the extraction process, after all the sugar has been taken out is called molasses in Britain and Black strap in the US.
Golden Syrup, a product little known in America is a light golden mixture patented by sugar refiners Tate and Lyle. It is a highly concentrated solution of sucrose, invert sugar ( a mix of fructose and glucose) and some added non sugars which give it is distinct flavour.
Treacle is a dark sweet syrup made during the process of refining sugar. All these products are used extensively in baking and confectionery, cakes puddings etc. Molasses, Black Strap and Treacle add colour as well as flavour to anything to which they might be added.

Black treacle is sometimes called '' dark molasses", but it's different from Blackstrap molasses.  Black treacle is sweeter and has a lighter taste than Blackstrap molasses - Blackstrap has a much stronger liquorice taste to me.  In cooking, I find black treacle slightly runnier.  There is a clear explanation on Wikipedia:

en.wikipedia.org molasses is made from young sugar cane. Sulphur dioxide, which acts as a preservative, is added during the sugar extraction process. Unsulphured molasses is made from mature sugar cane, which does not require treatment with sulphur. There are three grades of molasses: Mild, or first molasses; dark, or second molasses; and blackstrap. These grades may be sulphured or unsulphured.

To make molasses, the sugar cane plant is harvested and stripped of its leaves. Its juice is extracted from the canes, usually by crushing or mashing; it can also be removed by cutting. The juice is boiled to concentrate it, which promotes the crystallization of the sugar. The result of this first boiling and removal of the sugar crystals is first molasses, which has the highest sugar content because comparatively little sugar has been extracted from the source. Second molasses is created from a second boiling and sugar extraction, and has a slight bitter tinge to its taste.

The third boiling of the sugar syrup makes blackstrap molasses. The majority of sucrose from the original juice has been crystallized, but blackstrap molasses is still mostly sugar by calories.[2] However, unlike refined sugars, it contains significant amounts of vitamins and minerals. Blackstrap molasses is a source of calcium, magnesium, potassium, and iron; one tablespoon provides up to 20% of the daily value of each of those nutrients.[3][4] Blackstrap, often sold as a health supplement, is also used in the manufacture of cattle feed and for other industrial uses."

Molasses is a residue from sugar refining. When cane or beet sugar is produced it leaves behind a thick, treacly brown gluey liquid that has many uses. Made up of sugar, water, mineral salts and nitrogenous substances molasses is sold as black treacle when it is from cane sugar and can be used in many types of baking and cooking. Treacle is a traditional sweet glaze for baked ham and is often included as an ingredient in Christmas cakes. It should be the main ingredient in treacle tart but modern recipes tend to specify golden syrup instead. Sugar cane molasses is also used to make rum. Sugar beet molasses is an ingredient in animal feeds and is also used to make industrial alcohol. The name molasses comes from the Portuguese "mellaço" which was itself derived from the Greek for honey "mellas". One interesting fact about molasses is that it is a chelating agent. This means it can reverse molecular processes affecting metals. A rusty piece of metal immersed in molasses will eventually return to a shiny condition.

The above information is good to have, but doesn't answer my question. I need to know which flavours are stronger or more delicate.  I recently made a dark rye bread and the American recipe called for molasses. Here in Australia I only had treacle which I used. The flavour of the bread was a bit sharp with a bitter twinge. Not happy.  I needed some sort of 'graded' information.....use this one with heavy bread, this one with more delicate cookies or cake.....

Can you provide that information along with how the different grades of molasses and treacles affect the flavours...?   Thank you,
  Eve

Golden Corn Syrup (light or dark) is not the same as Golden Syrup. Golden Syrup is made from sugar cane whereas Light/Dark Corn Syrup is made from corn. The cooking temperatures and other properties of the cane vs corn sugars are different and they cannot be substituted in most recipes. I have had multiple failures trying to make Australian Caramel Slices using various other sugars (corn, barley, etc). Caramel Slices will come out runny with non-cane sugars. I haven't found a substitution in the US so have to import proper golden syrup for my recipes.

Molasses is a thick, brown to black, honey like substance made when cane or beet sugar is processed. It is used as a sweetener in many countries, and most particularly in England where it is called treacle.

Molasses is an mother liquor  that got from an sugarcane juice.

Molasses is an mother liquor  that got from an sugarcane juice.