On the Semantic Web, vocabularies define the concepts and relationships (also referred to as “terms”) used to describe and represent an area of concern. […] There is no clear division between what is referred to as “vocabularies” and “ontologies”. The trend is to use the word “ontology” for more complex, and possibly quite formal collection of terms, whereas “vocabulary” is used when such strict formalism is not necessarily used or only in a very loose sense.

Reference W3C: https://www.w3.org/standards/semanticweb/ontology

Steinbeis Transfer Centre IMCHI has been involved in the implementation of vocabulary web services in various research projects.

Within one of these projects the Tematres software was used to implement vocabulary webservices based on standard formats.
This link leads to a test installation of the UNESCO thesaurus: