The rise of digitalisation, network externalities, and data as novel sources of competitive advantage has fundamentally challenged traditional doctrines of competition law. With the adoption of the Digital Markets Act (DMA) and the Digital Services Act (DSA), the European Union has established an ex ante, preventive regulatory paradigm designed, among other aims, to avert market distortions caused by gatekeeper platforms. By contrast, the United States continues to rely primarily on ex post enforcement, precedent-based adjudication, and judicial processes in governing digital service markets. The divergence between these two models reflects deeper economic-philosophical and legal-policy differences; however, an emerging tendency towards convergence can be observed in their shared recognition of the democratic and geopolitical significance of digital markets. The evolution of competition law in recent decades has been profoundly shaped by digital corporations, which have redefined the conceptual boundaries of global market structures. A comprehensive understanding of contemporary legal practice and regulatory developments therefore requires a systematic examination of the theoretical divergences and convergences, and of the underlying explanatory factors shaping both regimes.