Structural changes between different versions of a software artifact are important for engineers in understanding its evolution during the development process. This paper presents a novel approach for the detection of structural and textual differences between versions of a software artifact. The approach is distinguished itself from existing ones by a novel directed graph-based representation model for artifacts and a structure-oriented configuration management repository that is capable of managing both textual and structural changes. It can also support compound documents containing objects with multiple nested levels. Structural differences can easily be retrieved, highlighted, and visualized side-by-side. We have successfully applied the approach to build a set of structure-oriented difference tools for various types of software artifacts such as source code, XML-based structured documents, system architectural design documents, entity relationship diagrams, and database tables. These tools are very efficient since they do not involve the difference computing algorithms for complex data structures (e.g. trees or graphs) as in existing tools.