ARM is both a company and an instruction set used in CPU's. ARM and x86 (used by Intel) are sets of instructions that a CPU can understand and execute. This depends on the architecture the actual silicon is built on. Hence, synonymous to CPU architecture. While Intel CPU Cores are directly sold to manufacturers. ARM, the company which might be acquired by Nvidia, licenses the standard for other companies to design chips for their own devices. This enables manufacturers to build custom hardware tailor-made for their application. ARM offers the possibility for heterogenous computing. This allows CPU's to have different cores specifically built for different applications. A common example is a device with a multi-core architecture with specific cores for running machine learning applications.
Apple's shift to ARM processors for the Mac line-up were in the making for quite sometime. Maybe not in the form of chips for laptops. Apple have always been a proponent of building both the software and hardware for it's devices. Now they are going all the way. They have really understood the synergies that would bring. It had substantial cascading effects to the feature-set and user experience of their devices. But hardware is hard. Apple chose which components were strategic to it's product in the future and invested in them. They were successful in doing that for the iPhones and iPad. These devices run on ARM processors that were designed by Apple but manufactured by other companies like Samsung
A moat around apple devices is the high switching costs. Once you are in the ecosystem, it becomes increasingly hard to switch to another platform. A main reason why they were able to make this work is the continuity it's devices offered. They gave seamless a new meaning with features like AirDrop. It just works. Moving all their devices to ARM processors could mean they are saving even more development cost, as now they don't have to develop for different platforms. They could migrate features and functionality on the OS and drivers they have perfected over the years in the iPhone to the Mac line-up.
From a business point of view, owning the design of chips meant that they could save a lot. Intel integrated design and manufacturing and charged heavily for their design services. Now Apple can keep those margins for themselves and outsource manufacturing to companies like TSMC.
