Common Taxonomy Questions: What is the difference between a Taxonomy and an Ontology?

In the world of information management, two common terms that people use are "taxonomy" and "ontology" but people often wonder what the difference between the two terms are.  In many of our webinars, this question comes up so I wanted to provide an answer on our blog.

Taxonomy is a collection of terms that are connected by broader term, narrower term, related term, and synonym relationships. You can think of taxonomy as a tree, with parent/child relationships between the terms.  A taxonomy generally is limited to a specific subject area, for example Products or Medical Conditions.  Taxonomies are valuable when you want to add structure/context to unstructured information to make that information more easily searchable, For example, if a taxonomy is used to tag documents in a search index, then when a user does a keyword search of this content, the Taxonomy can be presented on the left hand side of the search results as filter options for the end user.  Multiple taxonomies can be combined together as filters to make for a powerful drill down search experience.  This is what you  see on many leading ecommerce sites like Amazon or Costco.

Ontologies can be thought of more like a web, with many different types of relationships between all concepts.  Ontologies can have infinite number of relationships between concepts and it is easier to create relationships between concepts across different subject domains.For example, you could create a relationship between the topic of "Wood" in a materials taxonomy and "Chair" in a products taxonomy. Relationship types could be "example of", "Purpose of" or "Part of".   Ontologies would be used when wanting to create a more sophisticated information model that might be deployed to do advanced natural language processing or text analytics.  Ontologies would allow you to better understand things like cause and effect between two concepts within a corpus of information.  Ontologies can also power question answering engines: for example, if I search for "Who was the 16th president? ", an engine leveraging ontologies could return a specific result of "Abraham Lincoln"

Many of the taxonomy available from WAND are truly "taxonomies". An application like SharePoint 2010 or SharePoint 2013 can support Taxonomy structures but not ontologies and usually, for tagging documents, a taxonomy is a great solution.     However, the WAND Product and Service Taxonomy is actually an ontology because of the attribute and attribute values.  For example, we have a category of "Laptop Computers" which is a narrower term of "Personal Computers and Accessories".  Laptop Computers also has a relationship with the Brand "Toshiba Satellite" because Toshiba Satellite is a "Brand of" laptop computers.

WAND is a leading provider of taxonomies. If you are looking to build taxonomies or ontologies for your organization, find out how you can access the WAND Taxonomy Library Portal to be able to browse and download any of the WAND Taxonomies.