BIM is more than a 3D modeler. Other software packages, like SketchUp, Rhinoceros, Autodesk Alias Studio, Autodesk Maya and Autodesk 3ds Max, are excellent modeling applications.
However, these modeling applications don’t have the ability to document
your design for construction or to be leveraged downstream. This is not to say these tools don’t play a part in a BIM workflow.
Many architects use these tools to generate concept models, which can then be brought into a BIM application and progressed through design, analysis, and documentation.