I am not talking about the chemical difference (sugar is chemically a molecule formed by two monosaccarides: glucose and fructose). I am wondering about the difference from the cooking point of view in using pure glucose syrup vs. a syrup made of simple kitchen sugar dissolved in water.
Pure glucose is significantly thicker than a sugar syrup you would make on your own. It's even thicker than honey. At the previous restaurant I was at, we would use glucose in some limited applications when making certain kinds of caramel sauces (sorry, I didn't steal any recipes before I left), as (if I recall correctly) it has a higher tolerance for heat, and provides sweetness without caramelizing at the same temperatures as table sugar.