AutoCAD is a Computer Aided Drafting program sometimes referred to as CAD, however there are different versions of the software which are available and in which I am certified by Autodesk, the company who writes the software, at the Instructor level.
1) There is Autodesk's "Flagship" version which some users refer to as "plain vanilla" because it is very diverse and as a result, used in many different fields. Most AutoCAD users learned on this version. I began teaching AutoCAD in 1991 at a 2 year college where since then I have taught 18 different versions starting with release 10 for DOS and every release since then up to and including the latest which is release 2012 for Windows.
2) There are Autodesk's specialized versions of AutoCAD, in which I am certified and also teach. One known as AutoCAD Architecture which is used primarily by Architects that is more of a 2D/3D modeler which has a variety of different types of walls, windows, doors, etc. built in to the program.
Another specialized version of the program in which I am certified and also teach is AutoCAD MEP which is used primarily by Engineers. It is also a 2D/3D modeler that is used in the field by Engineers that specialize in Building Systems such as heating & air conditioning, electrical systems and plumbing.
Prior to teaching AutoCAD, I am required by Autodesk and my Employer to pass a test, which I have for every release of AutoCAD.
Revit falls into a category of software referred to as BIM or Building Information Modeling. It is an intelligent model-based program that provides insight for creating and managing building projects faster, more economically, and with less environmental impact. By collecting and updating real-time model data, BIM enables Architects and Engineers to create, communicate design intent, and understand performance, appearance, and cost (construction & operating) early in the building design process. In an age where more and more municipalities are insisting on the development of "Green Buildings", the design of buildings in Revit has become a requirement on Government Projects in most big cities.
Having realized the above in 2007, I went to work for Eberhard Systems, an Autodesk reseller who, knowing my background was willing to invest in sending me to different Autodesk facilities in places such as New Jersey, Rhode Island and Las Vegas to have me get trained in Revit. With all of the concentrated class work by Autodesk's finest under my belt, I took the exam that same year and every year since and got certified in Revit and the yearly updates.
Much like AutoCAD, Revit is available in three (3) different specialized versions which I am certified in at the Instructor level:
1) Revit Architecture is a program that comes with Parametric Components also known as families. They are intelligent objects. The program comes with a library of these families which could be windows, doors, lighting, furniture, etc. The power of these parametric objects lies in the fact that you can edit them as far as size, material or anything you want to change. Since you are in the fact building a database that contains all the objects you have placed in the model, if you make a change to an object in one view, it changes everywhere. I showed this to one Architect and I thought he was going to faint.
2) Revit MEP works in a similar way as Revit Architecture except that the Engineer(s) that is designing the heating and air conditioning, electrical system and plumbing has the tools to enable them to use the Architect's model and let Revit MEP use the design loads to design the various systems the building will need. Revit MEP also has a library of parametric parts that can be manipulated to fit the design parameters required. There are also 3rd party add-ons available which based on the geographic location and orientation with respect to north, will produce a report that will give you the cost to construct and operate. Another feature that is built in to the program tells the MEP Engineer if there is going to be any interference between objects for example pipes and ducts or any physical objects in the building prior to construction, avoiding costly mistakes prior to construction.
3) Revit Structure is also a parametric modeler much like Revit Architecture and MEP. Autodesk Building Information Modeling (BIM) software enables structural engineers to improve multidiscipline coordination of structural design documentation, minimize errors, and enhance collaboration between engineering and architecture teams. Autodesk Revit Structure software is the BIM solution for structural engineering firms, providing purpose-built tools for structural design and analysis. The Structural Engineer using Revit Structure uses the Architect's model and the tools in Revit Structure to design a structure to support the imposed loads even if the Architect makes changes in the design.
Prior to teaching and supporting all three (3) versions of Revit, I am required to pass a test, which I have for every release.