What I mean is that services CAN BE hooked into the OS. My messaging service being independent from my messaging app (sms as an example.) What I mean is, by default, Google has best in class services. (Photos and Maps are clearly superior to Apple.)

Being able to SET my default maps service. I need the os to be aware of what kinds of queries my maps app can handle.

Being able to swap out my voice assistant between google, alexa, cortana, m. I need the hardware and os layer listening, ready for me to trigger my voice assistant, but once they do, they should had it off to the service of my choice. Or my Roku being able to deep link directly to content within apps, apps that advertise their content to the os search.

Android is built to allow google, a manufacturer, or a user to swap out services, but still allows the service to feel integrated.

I do think there is a distinction between Android and Google Play Services. GPS is an advantage, and a great set of default services, but im not stuck with them for the life of a device, if I choose to replace them.