What is the difference between Android 7 and Android 8?

• Notifications: Grouping notifications into channels (Notification Channels), ability to snooze notifications.
• Background restrictions: Reduced limits on background services and broadcast receivers to improve energy efficiency.
• Picture-in-picture (PiP): Native support for "picture-in-picture" mode for video applications.
• Autofill: Platform support for autofill services for forms and passwords.
• Adaptive icons: Ability to create icons that change shape.
• Text selection: Improved context menu when selecting text with action suggestions.
• API level: Android 7.0 (Nougat) corresponds to API level 24, and Android 8.0 (Oreo) — API level 26.
• Vitals: A set of improvements in performance, stability, and battery life.

The main development differences are related to stricter background restrictions and new APIs for notifications, autofill, and PiP.