This paper presents an approach for comparing two architectures for ontology-based semantic annotation for service interoperability, the EMPOWER architecture using platform specific XML-based technologies and the MEMPOWER architecture extending this with platform independent Model Driven Architecture (MDA) based technologies. We will compare the two architectures with respect to pilot requirements and experienced advantages and challenges for model driven systems. The two approaches are being evaluated based on examples from interoperability between ERP-systems in a Buyer/Seller interaction context.