2D: Only 2-dimensional flat.
3D: Contains 3-dimensional (x, y, z) and can be manipulated from several points of view.
4D: The notion of time to a project (phases or sequences)
5D: The concept of the cost of a project (estimated)
6D: The management of the building (Heritage management or FM)
Each of these concepts take it in the source and BIM can make an enormous difference to a project.
Here are some software that will allow you to use the BIM in these concepts:
4D: Innovaya, Naviswork, MS Project
5D: Excel, Innovaya, Timberline
6D: FM Desktop, Archibus