BIM = Building Information Modelling = Modelling of Information of Building = 3D graphical model + information.
CAD = Computer aided design.
Apart from the 3D graphical part implied by the term "model", the feature rich information part distinguishes BIM from CAD.
4D BIM = 3D graphical model & information + time information.
5D BIM = 4D BIM + cost information.
6D BIM = 5D BIM + facility management information.
QTO = quantity take-off = measurement of quantities.
Revit is one of BIM software.