Leopard added 64-bit support throughout the system frameworks, so any app can be 64-bit.Tiger added 64-bit support for low-level system libraries, enabling 64-bit for non-GUI applications.The short answer is that Leopard is a mix of 32-bit and 64-bit. 17.4k 17 17 gold badges 75 75 silver badges 120 120 bronze badges 4 Answers