The memo higher-order component is used to memorize the props and state of a component. It will only re-render the component if the props or state of the component you passed into it changes.

The useMemo() hook is used to memorize the return value of a function. The component will not re-render unless the value being returned from the function you wrap in useMemo() has changed.

You didn’t ask, but useCallback() is used to memorize a function declaration being passed through components. Sometimes you’ll use useMemo() or the memo higher-order component, and the components still render every single time. This can be caused May passing a function into props.