What is the difference between useMemo and useReducer?

useMemo: caches the result of calling your function it caches the result of calling the input function so that it doesn’t change unless the product has changed. This lets you pass the requirements object down without unnecessarily re-rendering ShippingForm. When necessary, React will call the function you’ve passed during rendering to calculate the result.

useCallback: caches the function itself. Unlike useMemo, it does not call the function you provide. Instead, it caches the function you provided so that handleSubmit itself doesn’t change unless the productId or referrer has changed. This lets you pass the handleSubmit function down without unnecessarily re-rendering ShippingForm. Your code won’t run until the user submits the form.