Strong rhetorical differences between the European Union and the United States on climate matters have been evident for almost two decades. Since the mid-2000s, such differences are becoming visible in their respective climate policies as well. We propose three explanations for differences in climate policy outcomes in the EU and the US. First, the agenda-setting privileges of their policy-makers are significantly different, influencing how agenda setters shape policies and link issues, such as energy and climate policy. Second, while issue linkage has helped overcome distributional obstacles in the EU, it has led to more complexity and greater policy obstacles in the US. Finally, legislative rules, procedures, and norms have constrained the coalition-building efforts of lawmakers in the two systems in different ways, affecting negotiation processes and outcomes. Such differences in agenda-setting privileges, potential for issue linkages, and legislative procedures in the EU and the US have left them wide apart in international climate negotiations.