Let's just take this off topic. You are correct in this. Even the not from concentrate juices, let's say orange since it's the most prevalent example, is pasteurized which takes away all the orange flavor. So they add natural orange flavoring to get the juice that perfect flavor for their brand.
As you say the 100% juice can and is still made with concentrates. It's when they take a concentrated juice, add water and other sugars, then they can't claim it's 100% juice, but it is still labeled as juice. Versus a drink, which is mainly water and sugar, like Sunny D. Fruit Drink. Both not healthy. Just juice your own and don't go overboard unless you like sugar spikes.