This chapter evaluates the differences in the operations of the Asian Infrastructure Investment Bank (AIIB) and the Asian Development Bank (ADB) in relation to their development mandates, operationalized through different investment modalities and strategic decisions. It examines variation in project selection, sector focus, financing tools, approval procedures, and the use of co-finance and alliances, leading to varied risk profiles and implementation trajectories. The chapter further evaluates how the governance structure, policy frameworks, and institutional positioning of each bank influence strategic priorities, especially the region’s infrastructure, sustainability, and connectivity, and identifies areas of convergence in practices due to standard harmonization and/or coordinated procedures. The chapter sheds light on how the two financial institutions, AIIB and ADB, distinguish their portfolios while remaining functionally compatible by mapping their similarities and differences, thereby laying the groundwork for understanding their broader pattern of interaction in the Asian region.