https://www.cnet.com/news/google-android-pie-versus-apple-ios-12-guess-whos-winning-now/

Although Apple and Google are located about 9 miles away from one another in the heart of Silicon Valley, their philosophies are worlds apart.

Google's Android OS is about openness (but that can lead to fragmentation), whereas Apple's iOS is about making a tight system work well (but many services only function within Apple's relatively narrow device ecosystem).