A taxonomy in Drupal (and GovCMS) is a way to classify or categorise certain types of content.
A vocabulary is a group of taxonomy items. A vocabulary can only be used to categorise one type of content. For example, only the Event categoriesvocabulary can be used to categorise content of type Event.
These terms and the distinction between them is best illustrated by an example. News articles can be classified or categorised by the State/Terriroty they relate to. The categories or taxonomy items would be ACT, NSW, QLD, NT, SA, TAS, WA. The vocabulary in this example would be called State.
View vocabularies and taxonomy terms (items)
To see the list of vocabularies available to use on a site, hover over Structure on the Admin menu then click Taxonomy.
Image of taxonomy menu
Click on the List terms to the right hand side any of the vocabularies listed to show the list of taxonomy items it contains.
In the screenshot below, the list of News categories (taxonomies) is listed.
Image of News categories
Add a taxonomy item to content
When creating content of type News and Media, content authors can apply a Category (taxonomy item) to the content. Only the vocaulary of News categories can be used for the News and media content type.