What is the difference between Android one and Android pie?

Android One: These devices mean up-to-date Android OS. Recently, Google has released Android Pie. It comes with major improvements like Adaptive Battery, Adaptive Brightness, UI enhancements, RAM management, etc. These new features help old Android One phones to stay in pace with new ones.

Which is best Android or Android one?

Android One is the Stock Android for non-Google hardware users. Unlike custom Android, Android One has faster updates. Better battery performance, Google play protect, optimized Google Assistant, minimal bloatware, artificial intelligence from Google, more free storage space, and optimized RAM are some of its features.