Right off the bat, juvenile courts and criminal courts differ from their very intent. With the latter, as far as prosecution is concerned, the idea is to accuse an individual or party of one or more crimes, indict them on those charges, and prove their guilt to a jury of the defendant's peers beyond a reasonable doubt. If found guilty, the defendant should receive a sentence proportionate to his or her crime.
In juvenile court, on the other hand, it is not the State's constituents' best interests that are represented, but those of the child's which must be assessed. In fact, juvenile courts do not necessarily have to hear a response to a criminal complaint. Certainly, a child could be at risk of delinquency, and thus, must need to formally appear before a judge, but their physical, mental and emotional health could be at risk as well, necessitating swift intervention on the part of the courts.
A concept which is ever-present in juvenile law and juvenile court is the doctrine of parens patriae, roughly translated as "the state as parent." A juvenile court shares certain identifying features with a "regular" court of law. Yet, by the same token, juvenile courts have some notable departures from the template of their adult counterparts.
As hinted at, a juvenile court judge is the ultimate arbiter of any prescribed course of action, not a jury. Moreover, while most criminal courts operate for all the world to see, the affairs of juvenile courts are made private for the sake of the child and the sensitive information therein.