Model-based approaches in the UML/MOF technological space and ontology-based approaches in the OWL technological space both support conceptual modeling using different kinds of representation and analysis technologies. Both spaces provide services for accessing and manipulating models and ontologies, respectively. This paper compares both spaces using to a mapping of models and ontologies based on a common model-theoretic semantics. Based on this mapping, different services for bridging the respective technological spaces are defined and discussed. Three different bridging strategies, namely Adaptation, transformation, and integration, are distinguished.