Sugar is sugar is sugarFructose is the derivative of fruits and yes, corn, though from corn it is typically converted into a high fructose corn syrup, which equals bad news for your health.Fructose is not a "health" food, because it is a sugar, similar to glucose, lactose, and sucrose. I believe fructose is an inverted sugar, though please correct me if I am wrong, which means it is broken down into two simple sugars, glucose and levulose, and this is good because it prevents crystallization, which in turns prevents sugar "weeping." Regardless, the body consumes sugar, with and without all the carbs, similarly. It may be better for the digestive system if you purchase a product that has little processing.
You have to process sugar to make sugar. It cannot be "all natural," but there are levels to the processing. Sucrose can be made into a fine granule, or even demerara, a hard and large granule of sugar in which molasses has been reintroduced. The variety of sugar you would want to use depends on the application. I would use fructose if I wanted a very clean and pure taste with some pastry products. I would use demerara, sucrose, if I wanted something with a strong molasses flavor, especially when cooking with a southern american cuisine.
I hope this helps with some of your questions. You can also use lactose, a less sweet sugar derived from milk, if you wanted something to assist in blood sugar development that isn't as sweet as regular sugar. There are so many different forms of sugar available, but don't get the impression one sugar is necessarily better than another, though I would include high-fructose corn syrup as an exception, just like I would say hydrogenated shortening is a more unhealthy fat than other forms of fat, such as oils and butter, because of the processing.