So far you could safely equate 64-bit ARM processors with ARMv8 architecture. Not anymore. A few months after introducing Cortex A35 low power ARMv8 64-bit processor, ARM has now announced Cortex-A32 processor, even more power efficient, support ARMv8-A architecture, and designed for 32-bit embedded and IoT applications.
So they’ve got rid of AArch64 instruction set out of ARMv8 architecture in order to improve power efficiency, while keeping the 100 new instructions part of Aarch32 to improve performance, and keeping ARMv7-A compatibility.
ARM also claims the performance will be the same as Cortex A35, and close to Cortex A9, with gains in integer workload efficiency of respectively 10, 25, and 30% over Cortex A35, Cortex A7, and Cortex A5. Thanks to the lack of 64-bit support, Cortex A32 is also 13% smaller than Cortex A35.