Final answer:
An alliance is a union or association between countries or organizations for mutual benefit, which can manifest as different economic agreements like free trade associations, common markets, and economic unions. In the labor context, a labor union is an entity that represents workers' interests.
Step-by-step explanation:
A union or association formed for mutual benefit, especially between countries or organizations, is best described as an alliance. An alliance can fall under various forms such as a free trade association, a common market, or an economic union. For example, a free trade association offers free trade among its members, but allows individual countries to maintain their own external trade policies, while an economic union involves a higher level of integration including coordinated fiscal and monetary policies among its members.
In the context of labor and employment, a labor union is an organization that represents workers to negotiate with employers over compensation and work conditions. Labor unions play a significant role in advocating for fair wages, safe working conditions, and benefits on behalf of their members.