A type identifies the kind of entity being described, such as Organization, Article, or Product, and the name and properties of the object. JSON-LD is one format for carrying this vocabulary and is not the same concept as Schema.org.
To choose the right type for your site, start by determining the main subject of your actual pages. Avoid adding extraneous markup just because there are many types available.
Not all types defined by Schema.org are supported as rich results in search engines. Check the validity of data representation and support conditions for specific search functions.