Internal navigation directs users to a location within the same website or interface. For example, navigating to the products page from the homepage of the same website is internal navigation.
External navigation is when a user clicks a link and is redirected from one website to another. For example, a user on the Codecademy website clicks a link and is redirected to YouTube to watch a video. This is considered external navigation because the user travels from one website (Codecademy) to another (YouTube).