Though React.memo and useMemo both help optimize performance in React apps by avoiding unnecessary computations or re-renders, they are used in different situations:

Aspect	React.memo	useMemo
What it optimizes	Component re-renders	Expensive calculations or derived values
Usage target	Entire functional components	Inside functional components
How it works	Memorizes the component output (render)	Memorizes the return value of a function
Syntax example	React.memo(Component)	const memoizedValue = useMemo(fn, deps)

Example of React.memo:

const MyButton = React.memo(function MyButton({ label }) {
  return <button>{label}</button>;
});

The MyButton component won't re-render if the label prop doesn't change.

Example of useMemo:

const sortedItems = useMemo(() => {
  return items.sort((a, b) => a.value - b.value);
}, [items]);

Here, sorting only happens again when items changes.

Summary:

• Use React.memo when you want to optimize entire components.
• Use useMemo when you want to optimize expensive computations inside components.

---