Theme has option to have reviews in posts and in products. They can look similar but work with different purposes and have different additional options.
Posts – don’t have any filtering, attributes. So, if you want to build something like directory listings, use Woocommerce products reviews. But posts can have more advanced User’s ratings with criterias. So, if you want to build Review site – use posts
Products have prices, attributes, highly customizable, possible to filter by different values and orders. But user ratings in products are always 5 star rating. If you need advanced filtering, specifications and your site is more directory than recommendation or review, use Woocommerce products.
Here is tutorial about reviews in woocommerce products