Sort of right. Not all sugar is equal. The sugar in your soda? Not sugar at all as we know it. Try corn syrup. The further away sugar is from its pure form the worse it is for you. Corn syrup is used in almost everything now because its cheaper and subsidized. Hence the ethanol craze out of the Midwest. Milk and fruit juice have natural, simple sugars, which won't stick to your belly as easily. Listen when you hear the terms "processed food" and "refined sugar". They actually mean something.
The corn syrup that everyone has fits over is "high fructose corn syrup" which has had its glucose converted to fructose, the same sugar that is in fruit juice naturally. Fructose is fructose whether it has been processed from glucose or naturally occurring from the fruit. Chemically it is identical.
http://www.hookedonjuice.com/Now milk sugar is lactose, which some people can't process at all (lactose intolerant). But it is only about half the amount of carbohydrates per 8oz serving as juice or soda. But still, who only drinks out of 8 oz glasses.
Glucose, fructose, lactose, and maltose are all sugars and all affect your body similarly in the short term. Fructose based beverages have been shown to negatively affect your liver and response to insulin more than the other forms. Those include the fruit juice drinks as well. Fructose is used more than the other forms of sugar because it is cheaper than sucrose (table sugar) and glucose, maltose, and lactose just don't taste very sweet.