- App design changes introducing full-height sidebars and more integrated toolbars.
- Simplified Dock interface.
- Application icons now conform to iOS' Round Rect boxes.
- Notification Center now more iOS-like, with grouped notifications in-line with widgets, and all interactive.
- Safari: improved performance and energy consumption, new privacy protections, more customizable home screen, in-tab .previews, data breach notifications, privacy reports, on-system translation service.
- Messages: group tracking, contextual linking, pinned conversations, inline replies, mentions, group photos, improved memoji, stickers, hashtags, searching.
- Maps: new trip-planning tools, location research tools, guides, EV and bicyle-centric route planning, 3D look Around, Indoor maps.
- App Store: Safari Extensions get their own area, privacy information enhanced.
- Photos: retouch now Machine Learning enhanced.
- Peripherals: AirPods now automatically switch across devices using macOS 11, iOS 14, iPadOS 14 and later.
- HomeKit: improved face recognition and activity zones.
- Music: iTunes/Apple Music now Listen Now.
- Siri: better website integration.
- Software Update: improved updating mechanism; non-interactive bits happen in the background, update process sped up.
Big Sur was developed with Xcode as a dual-binary (referred to as Universal 2) that supports both Intel and Apple processors. Rosetta 2 will allow 64-bit Intel software to run in emulation on Apple processors. The first system provided by Apple to registered developers to run Big Sur natively on an Apple A12Z processor is the 2020 Developer Transition Kit.
Big Sur includes dynamic desktops, which change according to time and lighting conditions.