A common misconception around BIM has to do with its dimensions. The dimensions are different than the BIM maturity levels. BIM dimensions are inextricably connected to the type of data that can become available through the process. They can be found both in BIM Level 2 and Level 3.
In a nutshell, there are four types of BIM dimensions:
3D: It refers to 3D generated drawings, at this stage you are at just Level 1 BIM.
4D: adds project time management to the model
5D: adds project cost data to the model
6D: adds Facilities Management of the building in use to the model
Level 2 requires 3D plus time and cost data to be used, Level 3 BIM requires the link to building management, known as 6D.