How do composables differ from mixins?

Mixins (an Options API pattern) merge an object's options into the component, which can cause naming collisions and makes it unclear which mixin a given property came from, especially with multiple mixins.

Composables are plain functions called explicitly inside setup()/<script setup>, and you destructure exactly what you need:

const { x, y } = useMouse()

This makes the source of every property traceable, avoids naming collisions (you can rename on destructure), and composes cleanly — composables can call other composables. For this reason, composables are the recommended pattern in Vue 3 over mixins.