When you upload a file to your SiteNow website, there are various URLs to the file:
...file/id takes you to a node or "page" specific to that particular file. The user then has to click the filename presented in the node to view/download the file.
...file/[ID]/download will automatically tell the browser to download the file without any further action by the user.
...sites/[WEBSITE]/files/[FILENAME.EXTENSION] this is the "actual" URL of the file. If the browser supports the file format, it will display the file within the browser.
The File Node/File Download Advantage
The main advantage to using the File Node and File Download URLs is that if you ever upload a replacement or updated version, the URL stays the same. Anywhere that file URL is used will be automatically updated with the new file.