Both are CSV, XLSX, or XML files that contain the product information you choose. The difference lies in how that information is sent out.
A product feed URL has its own unique live link to keep product data up to date. That means you can just paste these product feed links (or feed URLs) to wherever you need to import the information. Then the feed will update the information automatically on the schedule that you want, so you don’t have to!
A product feed file is the downloadable version of that automatically-updated feed. Anytime that you want to send a spreadsheet to a marketplace or a customer, this is the option for you.