How is React Native different from React on the web?

The mental model transfers well: components, props, state, hooks and reconciliation all work the same way. What changes is the host environment. On the web the host elements are DOM nodes; in React Native they are platform views with a smaller and different API surface.

• No div, span, p or img: use View, Text, Image and Pressable
• No CSS files or selectors: styles are objects, often created with StyleSheet.create
• No window or document: use Dimensions, useWindowDimensions and AppState
• Navigation is a library concern such as React Navigation rather than the browser URL
• Storage, permissions, notifications and deep links all go through platform APIs

import { Pressable, Text, View } from "react-native";

export function Button({ label, onPress }: { label: string; onPress: () => void }) {
  return (
    <Pressable onPress={onPress} style={({ pressed }) => ({ opacity: pressed ? 0.6 : 1 })}>
      <View>
        <Text>{label}</Text>
      </View>
    </Pressable>
  );
}

Accessibility also differs. You use accessibilityLabel, accessibilityRole and accessibilityState rather than HTML semantics. Text must be wrapped in a Text component, and a View cannot directly contain raw strings.