What is the difference between facet search and attributes?

Faceted search which is also known as Product Filtering, is the feature that allows you to set up filters for your products on category, collection, or brands pages. It refines the product searches based on the attributes like price, color, size, etc. Facet search makes your website easy to use, bringing a better shopping experience for your customers. Faceted search is the flow of managing the filters in the sidebar as per the admin's convenience, you can manage which all attribute filters you want to display in the category sidebar and in which order through Faceted search.

A Facet group can have multiple fields and can define how they appear in the filters. To display the faceted search on the storefront, you need to define facet groups. For more information, you can visit - https://help.storehippo.com/topic/product-filtering-faceted-search
On the other hand, the Product attributes can be used to define the distinctive characteristics of a product, such as color, size, shape etc. Depending on the type of your product you can add various attributes to it that help in defining all the specifications of the given product. For example, if we have a table as a product, we can define its attributes as; shape (round or square), size (small, large), color, material etc. Product attributes can be visible on the Category as well as the Product page. For more information about the product attribute, you can visit - https://help.storehippo.com/topic/product-attributes