区别在于传递给通用寄存器以进行操作的指令集的位宽.16 位可以对 2 个字节进行操作，64 位可以对 8 字节的指令进行操作.您通常可以通过在每个时钟周期执行更密集的指令来提高处理器的吞吐量.

The difference comes down to the bit width of an instruction set passed to a general purpose register for operating on. 16 bits can operate on 2 bytes, 64 on 8 bytes of instruction at a time. You can often increase throughput of a processor by executing more dense instructions per clock cycle.