what is the term which differentiate the Apple A7 and Apple A8 system on a chips?
Apple A8 The Apple A8 is a 64-bit ARM-based system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 6 and iPhone 6 Plus, which were introduced on September 9, 2014. Apple states that it has 25% more CPU performance and 50% more graphics performance while drawing only 50% of the power of its predecessor, the Apple A7.
ARM Cortex-A75 The ARM Cortex-A75 is a microarchitecture implementing the ARMv8.2-A 64-bit instruction set designed by ARM Holdings. The Cortex-A75 is an out-of-order superscalar pipeline.