This webinar (featuring Andreas Blumauer, CEO of Semantic Web Company and Ian Piper of Tellura) explores both taxonomies and ontologies, and demonstrates how they work together to help you improve your knowledge modelling.
Ontologies form the framework, cabling, rules and practices within which your information needs to work. Think of a type of thing, and your ontology is effectively a way to describe how to put it together and make it work with other types of things. An ontology doesn't have to contain an actual thing; it's more like a template, or a recipe, for how a thing will look and behave. Taxonomies are more concrete entities. A taxonomy contains real things, and ideally these are things that conform to an ontology.
It's a bit like your word processor. You can create document templates in programs like Word. A template contains a set of styles and other constructs that will define how your document will have to look; headlines in a particular typeface and colour, body text in another, and so on. This is similar to an ontology. You don't actually have to create any content to create a document template. It just sits there waiting for the time when you want to create a real content-based document. Then it ensures that this new document conforms to the design you want, and looks and feels like other documents. This new document is analogous to a taxonomy; a taxonomy contains instances that conform to the design specified in an ontology.
Here is the webinar. It's about an hour long. We hope you find it useful.