A Taxonomy is a list of terms that enable classification of information
Typically expresses hierarchical relationships (parent/child)
Emphasizes context

A Thesaurus is a specialized taxonomy
Emphasizing relationships (synonyms, related terms)
Preferred terms, variant terms, AKAs

A Faceted Classification is a lateral taxonomy which allow for multiple classifications to an object

An Ontology is a collection of taxonomies and thesauri
A body of knowledge is represented by multiple lists of categories
Categories of various types are conceptually related