Labor law (also known as employment or labour law) is the body of laws, administrative rulings, and precedents which address the legal rights of, and restrictions on, working people and their organizations. As such, it mediates many aspects of the relationship between trade unions, employers and employees. In Canada, employment laws related to unionised workplaces are differentiated from those relating to particular individuals. (This would be handled by the Human Rights Commission)
In common law legal systems, the law is created and/or refined by judges. A decision in the case currently pending depends on decisions in previous cases and affects the law to be applied in future cases. When there is no authoritative statement of the law, common law judges have the authority and duty to make law by creating precedent. The body of precedent is called "common law" and it binds future decisions. In future cases, when parties disagree on what the law is, an "ideal" common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is bound to follow the reasoning used in the prior decision. (This would be handled in the Court of Queens Bench)
They inter-relate when existing Labour Laws don't cover legal situations leaving the decision to be made through common law. This often involves disagreements between employers and unions in the handling of contracts and agreements.
Juvenile law is civil and not criminal; designed to correct and not punish. A juvenile is not technically found guilty of committing a crime, as defined by penal law, but will be found to have engaged in delinquent conduct, as a result of their actions. Thus by a finding of the court "juvenile delinquency" has occurred.