Internal links are links that go from one page to a domain to a different page on the same domain. They are commonly used in main navigation.
An inbound link (also referred to as a back link) is a hyperlink on a third-party web page that points to a web page on your site. Inbound links are important for search engine optimization (SEO) because Google and other search engines see multiple, relevant inbound links to a page as a sign that the content on that page is useful.