@mntmn ARM maintains the ISA, but they have two license models.
The cheaper one gives a company access to particular predefined cores and other components to use in their chips. These interchangeable blocks have forced the blocks to be low-wattage jack-of-all-trades.
The architecture license means the produced chips have to conform to the ISA, but the ISA -> uOPs can be completely custom. Apple left out all 32-bit ISA, and added custom accelerators and tuning. Same engineers.