what is the difference between glucose and fructose structures?

They have the same formula but different structures.

It would be the arrangement of atoms that's different.

Glucose is an aldehyde, whereas fructose is a ketone.

http://nl.wikipedia.org/wiki/Bestand:Alpha-D-Glucopyranose.svg
http://nl.wikipedia.org/wiki/Bestand:Beta-D-Fructofuranose.svg

fructose is a 5 ring
glucose is a 6 ring
fructose has an extra CH2OH
that's basically it

Okay so in a clockwise direction, the Carbons are labeled from 1 to 6. However in Glucose, there are 5 Carbons on the base chain (6 if you include the Oxygen), and from the 5th Carbon, another Carbon branches out and connects to another Carbon and H2OH.

In Fructose however, there are only 4 Carbons in the base chain (5 including Oxygen). The same Carbon connects to another Carbon and H2OH. However, from the first Carbon, the OH which was originally in the Glucose chain is now Carbon and H2OH, just like the other carbon. So Fructose has 2 Carbons branching out of the main chain, while Glucose only has 1.

Hope you understand lol.

Fructose and glucose are both monosaccharides with the same chemical composition but a different molecular structure.