There are four basic types of "pages". It is better to speak of different navigation points, since not every "type" is a page.
1) The home page. In the picture named "Home". In other systems, the home page is often the first page in the navigation tree. With page4, it doesn't matter where the home page is placed in the navigation tree. It also doesn't matter how this page is named. There can be only one start page. If you mark a new page as "start page", the previous start page loses this status and becomes a normal page again. The only difference to a normal page is that the start page is the page that is displayed when a visitor calls the domain of your homepage. Otherwise, the home page "can" do almost everything a normal page can do with the following differences: A home page cannot be set as a draft. You cannot simply delete it. And you can't move the home page to the clipboard.
2) Normal pages. Also named as "Normal page" in the image. Most pages of your website will be normal pages. A normal page has an entry in the navigation (but you can hide it) and can hold content.
3) Folder. Also named as "Folders" in the image. Folders are not pages. They are simply entries in the navigation with a single option: folders can "hold" any number of pages and links and then display them as subpages. If a folder has pages as subpages, the first page is always called when you click on the folder in the navigation. If a folder has no pages at all, then clicking on it in the navigation will have no effect.
4) Links. Named as "linking" in the image. Links are not pages either. They are entries in the navigation, which have a link. You can link to external or internal pages. If you click on the link, the stored link is executed.