High fructose corn syrup used in most foods is about 55% fructose and 45% glucose. Sucrose (cane sugar) is 50% fructose and 50% glucose. The only difference is the rate of absorption.
You are correct about the composition of sucrose. The problem with HFCS is that it does not generate the same metabolic response as sucrose. Leptin is part of the satiation response to sucrose/glucose. People will unconsciously consume more fructose than sucrose. The glucose is metabolized in all of the muscles and fructose must be metabolized in the liver (fat generating consequences).
Fructose also causes the absorption of extra iron in the gut. Iron is a major component in diabetes, heart disease and cancer.