According to many baking/cooking sites, corn syrup outside the United States is called glucose syrup. That is not exactly right.
Although corn syrup is a glucose syrup, glucose syrup is not always corn syrup. They can be interchanged in some recipes BUT they can/do react differently.
In the United States, Legislators allow domestic food manufacturers to call glucose syrup "Corn syrup" because the source of the starch is almost exclusively from maize.
In other parts of the world, wheat, barley, tapioca, potato, rice, cassava, arrowroot, sago and maize starches are used to produce glucose syrup. The generic term of glucose syrup is used except when the originating material must be specified. Australian glucose syrup [liquid glucose] comes from wheat.
They all are aqueous solutions of several compounds, principally glucose, dextrose and maltose in various proportions.
Glucose syrup tends to be a thick syrup. Various ones can contain glucose levels up to 98%.
Corn syrup [US] is a thinner syrup. Old fashioned Corn Syrup contain high levels of glucose with some other sugars present.
The equivalence of 1/2 cup corn syrup plus 3 Tbs. water to 1/2 cup glucose plus 1/4 cup water produces the same results [usually].
Modern corn syrups contain between 15-98% glucose with other types of sugar. One source quoted some as low as 6-11% glucose content.
HFCS [High Fructose Corn Syrup] contains 42-55% fructose. While Fructose Glucose Syrup contains 20-40% fructose, it refers to American High Fructose Corn Syrup product for export overseas.
The 90-95% fructose corn syrup is becoming more common in beverages, canned fruits, confectionery products and dessert syrups.
I wonder when the labelling laws will kick in, and call a spade a spade.
I checked the Karo website:
Karo Light corn syrup: Light corn syrup, high fructose corn syrup, salt, vanilla.
Karo Dark corn syrup: Dark corn syrup, refiners syrup [cane sugar syrup], caramel flavor, salt, sodium benzoate, caramel color.