New technologies for shape acquisition and rendering of digital shapes have simplified the process of creating virtual scenes; nonetheless, shape annotation, recognition and manipulation of both the complete virtual scenes and even of subparts of them are still open problems. Once the main components of a virtual scene are represented by structural descriptions, this paper deals with the problem of comparing two (or more) sets of 3D objects, where each model is represented by an attributed graph. We will define a new distance to estimate the possible similarities among the sets of graphs and we will validate our work using a shape graph.