Rule-based systems (Castano and de Antonellis, 1999;Milo and Zohar, 1998;L. Palopol and Ursino, 1998) often utilize only the schema information (e.g., elements, domain types of schema elements, and schema structure) to define a similarity metric for performing matching among the schema elements in a hard coded fashion.
learning based approaches learn a similarity metric based on both the schema information and the data.