Starch is converted or broken down into glucose. Sugar (assuming you're referring to table sugar or sucrose) is broken down into glucose and fructose.
Whilst glucose can be used as fuel by most tissues in the body (i.e. muscles, organs, brain, etc) fructose can only be metabolised by the liver. Which might not be so bad, until your liver fills up it's glycogen stores and starts storing the fructose as fat - which can contribute to non alcoholic fatty liver disease. Fructose also signals the liver to absorb more glucose, and once again, once liver glycogen stores are maxed this will lead to an increase in palmitic acid production, and that may cause leptin resistance.
So, if your fit, healthy and active, a little bit of fructose (hopefully from real whole foods) will be fine, we've got the equipment to deal with it - in other words in this state you won't 'overfill' your liver glycogen.
However if you're over weight or obese / metabolically deranged, I'd avoid high fructose foods, including most fruits, like the plague.
Oh, and to answer your question, we're by far much better adapted to using starch/glucose as fuel, than fructose, so on that basic level, starch good, fructose bad.
SUGAR: depends on how you live your life: how active you are. Though i think we'd all agree that a spoon of table sugar is not good for anyone, active people could use that same spoon of sugar much better than say an obese person.
STARCH: Starch I would say is good for everyone. not that i think fat people should eat much of it, but once someone is healthy, normal bodyweight, etc eating starch is very good for you. Your body is built to metabolize starch - we have insulin for a reason, we have amylase in our mouths for a reason, you feel good when running on starch, etc etc. Not to the exclusion of meat and fat of course, but in complement.
Some kinds of starch are much worse than sugar. I am talking about beans and some kinds of grains. I am not talking about potatoes.
definitely sugar. starch has its place in a diet if you're active or run better with more starchy carbs. i treat sugar like alcohol. it's a poison and will kill you if you have too much. those who are insulin sensitive and have a healthy gut can probably get away with a little sugar
100% agree. I have had non alcoholic fattly liver disease and it is no fun...
Lost 25 pounds and dieted and it went away fortunately...
Fructose is a food additive in many packaged foods and it is just wrong...
I agree with mloster. And also remember that starch is just a bunch of glucoses strung together, but sugar is a glucose and fructose stuck together. Fructose is looking like it's much worse in terms of aging our tissues than glucose is.