The user can make a page only visible on a certain platform if they want to. They can make it so that certain pages will only show when viewing from PDF or when viewing from the view. This means that you can tailor certain pages for the audience of the web and PDF.
To do this, you will want to click the cog icon on the page you wish to change in terms of visibility for web and PDF. Clicking this will make a popup appear with the pages various settings. From this popup go into the PDF Settings tab, this shows the pages different settings for visibility with the web, PDF, and Index. Depending on where you want the page to be visible, you will need to toggle on or off the web and pdf options. Once you have decided where you want your page to be visible, be sure to click the Save button in the bottom right of the popup. Once you have saved your settings, if you go back and look at the pages again, depending on your settings, you will notice that the page now has a form of tag on it, either saying Web Only or PDF Only. This means that the page is either only viewable on the web with a URL link or is only viewable in a pdf which has been generated and downloaded by the user.