What is the difference between dublin core terms and dublin core elements vocabularies

There's 2 Dublin Core vocabularies DC terms and DC elements.

They define almost the same classes and properties.

So what is the key differences between them, and when to use each one.

Element Set:

• Namespace: http://purl.org/dc/elements/1.1/
• Predefined prefix: dc11
• It defines 15 terms.
• These terms are also published as the standards ISO 15836, ANSI/NISO Z39.85, and RFC 5013.

Terms:

• Namespace: http://purl.org/dc/terms/
• Predefined prefixes: dc, dcterms
• It defines all terms, including the 15 terms from the Element Set.

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Terms does not only include the 15 terms from Element Set, it defines terms with the same names as these 15 terms under its own namespace in addition. So, for example, there are two terms named coverage:

• http://purl.org/dc/elements/1.1/coverage
• http://purl.org/dc/terms/coverage

They should all have the same description. Differences:

• The 15 properties from the Element Set namespace don’t have a range / many of the 15 properties from the Terms namespace do have a range (rdfs:range).
• The 15 properties from the Terms namespace are sub-properties of the 15 same-named terms from the Element Set (rdfs:subPropertyOf).

Which one to use?

Unless you have a reason for using the terms from the Element Set (e.g., because of having to conform to the mentioned standards), go with the terms from the Terms namespace:

• Capable user agents can recognize that they are subproperties of the corresponding ones from Element Set (i.e., apply their meaning to your data, too).
• Capable user agents can infer things from the specified range.
• One less prefix to define in your RDF (if you use more terms from the Terms namespace).

This is also what the Element Set introduction recommends:

Implementers may freely choose to use these fifteen properties either in their legacy dc: variant (e.g., http://purl.org/dc/elements/1.1/creator) or in the dcterms: variant (e.g., http://purl.org/dc/terms/creator) depending on application requirements. The RDF schemas of the DCMI namespaces describe the subproperty relation of dcterms:creator to dc:creator for use by Semantic Web-aware applications. Over time, however, implementers are encouraged to use the semantically more precise dcterms: properties, as they more fully follow emerging notions of best practice for machine-processable metadata.