Fructose is an isomer of glucose meaning that it has the same molecular formula as glucose. The atoms are just in a different configuration.
There are also two separate isomers of fructose – D-Fructose and L-Fructose. Some people claim that most of the fructose in fruit is D-Fructose and most of the fructose in HFCS is L-Fructose. Some people also claim that the liver processes both isomers of fructose differently. I was never able to figure out if is true or not.
I don’t know if the fructose part of sucrose is D-Fructose or L-Fructose. If anyone knows for sure, please chime in.
Glucose comes in two isomers as well. Dextrose is another name for D-Glucose which is the type of glucose found in nature.
Personally through experimentation I have found that fructose leads to belly fat so I stopped using sugar all together. But if I was going to buy sugar I would definitely buy dextrose which is only 1/3 as sweet as sucrose.
There has also been a study that implies that HFCS makes rats fatter than sucrose does. I don’t know what to make of this since I have not read the study in detail.
http://www.ncbi.nlm.nih.gov/pubmed/20219526