Shared content (or reusable content) is content that can be used across multiple pages or sites.
A snippet is a pre-defined container of content designed to allow you to quickly add features to your site. For example, you may want to embed a YouTube video, add accordion dropown menus, create a visually interesting layout, or include a social media feed. With snippets, you can do that, and more!
Assets allow users a way to easily insert a block of content onto any number of pages. When that asset is updated and published, the asset will be updated on any and all web pages on which it has been included.
Learn more about shared and reusable content like assets and snippets in this video: