"What is the difference between an ontology and a database schema"? Since the early days of the now maturing ontology field, this has been a persistent question that has never been adequately answered. We define each concept for a high level comparison and then ask the following questions about each concept: 1) What is it for? 2) What does it look like? 3) How do you build one? 4) How is it implemented and used? and 5) Where are the semantics?
This gives rise to many other questions. For example: What is the role of constraints? of instances? Is there an analogy in ontology development for the process or database schema normalization? How is change management handled?
The differences between database schema and ontologies are many, varied and illuminating. Most arise from their different purposes and historical origins. There are also striking similarities. We wondered whether database schema and ontologies were more alike than different. We reached a surprising conclusion!