Choose Incremental Layout if you want the main arrangement of the graph to remain stable when you make changes to your project and only re-route the entities and links that have changed since the last rendering.
If you want to refresh the entire graph, click the desired layout option. The program has greater freedom to optimize the layout. The result is likely to be a more pleasing arrangement.
The hierarchical layout style indicates dependencies by positioning the nodes at different levels. The hierarchical layout style is useful when it is useful to show precedence relationships in the ontology. The hierarchical layout style indicates dependencies by positioning the nodes at different levels. You can use Layout Preferences to determine in the direction of the hierarchy. Preferences and options specific to the hierarchical layout are:
The algorithm places highly connected nodes closer together, resulting in a more compact graph. Even when lines overlap, the algorithm ensures that they are still easy to follow. Because this style has no hierarchical or other visual constraints, the resulting graphs are often very clear.
The symmetric layout style looks for and emphasizes the symmetries in a project topology. It can produce a pleasing visual result, if there are no reasons to arrange the nodes for other reasons, for example there is no hierarchy or ring-clustering inherent in the structure of the nodes.