Regional free trade zones like NAFTA and the EU have been successful in recent years. This paper looks at whether these trading blocs help or hinder global free trade. It compares two types of customs unions: one based on traditional comparative advantages and the other on economies of scale. The goal is to see how trade patterns within these blocs affect trade relations between them. The findings show that trading blocs organized around economies of scale can lead to expanded global trade, while those based on traditional comparative advantages may result in trade wars between blocs.