URL is an abbreviation that stands for "Universal Resource Locator." It's another name for a web address, the text that you type into your internet browser when you want to go to a website. A URL works like a house address. If you give someone a house address, they can navigate to find a home or business.
A link can be any text or image that you can click on that takes you to another page or file, either on your website or elsewhere on the internet.