The file library is much simpler but also works with S3 and local storage. To associate files to your model, use the HasFiles and HandleFiles traits, the $filesParams configuration and the files form field.
When it comes to using those data model files in the frontend site, there are a few methods on the HasFiles trait that will help you to retrieve direct URLs. You can find the full reference in the HasFiles API documentation
The file library can be used to upload files of any type and to attach those files to records using the file form field.
For example, you could store video files and render them on your frontend, with a CDN on top of it. We recommend YouTube and Vimeo for regular video embeds, but for muted, decorative, autoplaying videos, .mp4 files in the file library can be a great solution.