ActionBar is a primary toolbar within an activity displaying title and navigation. Appears at top of window by default in Holo theme since Android 3.0. Can be added manually using requestFeature or custom theme. Available as Toolbar widget since Android L (API level 21)
AppBar is the most used app component at the top of screen. Displays app title and relevant actions. Contains title, actions, backgroundColor, and elevation properties
NUI is an invisible interface that becomes invisible as users learn complex interactions. Unlike intuitive interfaces, NUI requires minimal learning through design. Users transition from novice to expert quickly through interface design
Company takes user-centered approach in all services. Designs focus on user experience and accessibility
iOS toolbars appear at bottom, aren't customizable or support grouping. iPadOS and macOS toolbars appear at top, support customization and grouping. macOS allows hiding toolbars, watchOS shows buttons in corners and bottom
AppBar is the topmost component of Flutter apps containing toolbar and action buttons. Built-in widget based on Material Design with MediaQuery and Scaffold support. Can be customized or replaced with SliverAppBar for scrollable functionality