Systems, methods, and software described herein provide enhancements for managing and comparing data from multiple information sources. In one implementation, a method of operating a comparison service includes obtaining, from a plurality of data sources, data objects in a plurality of formats corresponding to an event, wherein the data objects each comprise data items for the event. The method further includes maintaining a data structure for the event, wherein the data structure relates data items of similar data type from the plurality of data sources. The method also provides identifying a user request for a summary of the event, generating an event summary based on the data structure, and providing the event summary to the requesting user.