The rivalry explained in terms of Clayton Christensen's book The Innovator's Solution:
Modular architectures are often the solution when interdependent architectures prove too costly. Interdependent architectures are the solution when modular architectures are not good enough or can’t solve new jobs that users discover they need to solve.
Apple’s value systems, priorities and processes are all tuned to interdependent architectures. Google’s value systems, business models and competencies are all tuned to modular architectures.
Apple solves the problems of new markets, Google solve the problems of over-served markets.
So the winning strategy depends on detecting where a product lies in its march up the performance trajectory. Before it’s good enough, interdependent systems win. After it’s good enough, modular architecture wins.