Unlike realism - which posits survival and power as drivers and balance as mechanism - and constructivism - which posits ideas and identities as drivers and human interaction as mechanism - neoliberal institutionalism and neofunctionalism are two subsets of liberalism that focus on interests as drivers and institutions as mechanisms in determining preference fotmation and decision-making. In so doing, they offer a better explanation of international cooperation, integration processes, and institutional development than their theoretical alteruatives. However, both theories differ in terms of levei of analysis, key actors, and the causal mechanisms through which institutions are expected to condition policy outcomes.