The iPhone 5's A6 SoC: Not A15 or A9, a Custom Apple Core Instead
AnandTech:
The A6 is the first Apple SoC to use its own ARMv7 based processor design. The CPU core(s) aren’t based on a vanilla A9 or A15 design from ARM IP, but instead are something of Apple’s own creation.
And that’s why they can get better performance out of the same, or sometimes slightly less specs.
