There are more grams of sugar in 1 cup of grape juice(36) than in 1 cup of coca cola (26). Same for apple juice. It’s best to avoid all fruit juices.
http://www.livestrong.com/article/450038-juices-with-the-highest-sugar-content/
the difference between sugary drinks and fruit juice is nutrition not sugar. That is why the juice glass is so small.
If you want a sugar rush eat a spoonful of frozen apple juice. Man, is that good!