Not entirely true. A lot depends on the "package" that they arrive in. When the body has to work very hard to break down the "package" that the carbs or natural sugars are wrapped in, they take longer to be released into your system and don't provoke as much of a rise in your blood sugar and resulting insulin response. For example...if I were to eat 15 grams worth of carb of broccoli, the fiber in the broccoli takes a long time to be digested and broken down before those carbs can be converted to glucose and released into my bloodstream; probably anywhere from 45-50 minutes or longer and then in a slow stream. 15 grams of carb in the form of, say, a Hershey's kiss would hit my bloodstream in less than 15 minutes and pretty much all at one time. There would be very little rise in blood sugar from the broccoli and it would be in a low curve with very little insulin being released because of the slow release into the system, but a big spike from the Hershey's kiss with a resulting crash and a much bigger insulin response because of the rapid rise in blood sugar.
It's called the glycemic index and glycemic load; how fast a food can be converted to glucose and hit your bloodstream when compared to sugar along with how much it will raise your blood sugar as compared to sugar.