ARM vs x86: Licensing and Popularity
Another major difference between ARM and x86 is the way these two technologies are licensed. Although licensing obviously has no direct effect on performance, it does change the way these technologies can be developed and applied to new products.
Intel's x86 is effectively Intel's. The company guards the instruction set architecture jealously. AMD and VIA both have the ability to develop and build new x86 processors, but only because of old licensing argeements. AMD in particular has managed to keep its x86 licensing because it developed the 64-bit extension for the instruction set architecture, giving it some leverage. The only reason AMD got the license in the first place (we're talking early 80's) is because IBM wouldn't buy into Intel's 8086 (the first x86) unless there was more than one supplier.
ARM works much differently. The instruction set architecutre can be licesned (for a fee) by anyone who wants to build a processor. This has two effects. First, it lowers the cost overall cost, as it's much less expensive to license a instruction set architecture than try to develop your own. This makes designing an ARM into smaller, less expensive devices more practical.
Licensing makes it possible for a company to develop a custom solution for their hardware, which in turn results in better power efficiency and lower costs. Because Intel does not license x86, anyone who wants a x86 processor must buy a full processor from Intel (or AMD or VIA). ARM processors can be custom-tailored to a specific product.
This is why ARM Holdings, the company that licenses the ARM instruction set, often boasts that ARM processors are more popular than x86. They are, by unit volume, correct. There are far more ARM processors put into products because ARM processors can be custom-tailored to fit so many different roles, embedded into places where we don't even think of them, such as automotive technology.
Image Credits: The CPU Shack