For some people, they are much less healthful. For example, a glass of orange juice contains about one tenth as much fiber as an orange and twice the calories. Diabetics shouldn't drink fruit juices because they drive blood sugar levels too high, nor should people who are trying to lose weight drink fruit juices because a rise in sugar calls out extra insulin that makes you hungry. Don't be fooled by juices that claim that they supply 100 percent of your daily needs for vitamin C and A. Most drinks that can make that claim have artificial vitamins added to the drink and are no better for you than juices that have only 10 percent of your daily requirements. Adding calcium to fruit juices is reasonable because there are no known harmful effects and some people do not get enough calcium from other foods that they eat.
Manufacturers use terms that are deceptive.
If the juice in not made from real fruit, it is not juice. There is no known advantage or disadvantage to drinking fruit juice that has first had water removed to form a concentrate and then had the water added back in to form the juice. This process does not destroy nutrients and is not harmful. It really doesn't make much difference whether you drink juice that is 100 percent fruit juice or made from 50 percent sugar water and 50 percent juice. All juices contain around 8 to 10 percent sugar because that's the concentration of sugar that tastes best and that most people prefer.