SolidWorks is what we call a “parametric” solid modeller used for 3-D design. Parametric means that the dimensions can have relationships between one another and can be changed at any point during the design process to automatically alter the solid part and any related documentation (blueprint). AutoCAD, however, is primarily a 2-D design tool with some, but limited 3-D capabilities. It is very simple compared to any parametric solid modeller (although 3D is improved in AutoCAD 2007). Autodesk (the manufacturer of AutoCAD) makes a product that is nearly identical to SolidWorks, called Inventor, which is a parametric program for design of solid parts and assemblies.

SolidWorks is a 3D mechanical CAD (computer-aided design) program that runs on Microsoft Windows. SolidWorks files use the Microsoft Structured storage file format. This means that there is various files embedded within each SLDDRW (drawing files), SLDPRT (part files), SLDASM (assembly files), with preview bitmaps and metadata sub-files. Various third-party tools can be used to extract these sub-files, although the sub-files in many cases use proprietary binary file formats. SolidWorks is a parasolid-based solid modeller, and utilizes a parametric feature-based approach to create models and assemblies. Parameters refer to restrictions which values determine the shape or geometry of the model. Parameters can be either numeric, such as line lengths or circle diameters, or geometric, such as tangent, parallel, concentric, horizontal or vertical. Numeric parameters can be associated with each other through the use of relations, which allows them to capture design intent.

AutoCAD is, just like SolidWorks, a Computer Aided Design software application for 2-D and 3-D design and drafting. AutoCAD was one of the first CAD programs to run on personal or home computers, notably the IBM personal computer. At that time, most other CAD programs ran on mainframe computers or mini-computers that were connected to a graphics computer terminal for each user. Early releases of AutoCAD used basic entities such as lines, poly-lines, circles, arcs, and text to ultimately construct more complex objects. AutoCAD has since started to support custom objects through its C++ Application Programming Interface (API).

Modern AutoCAD includes a full set of basic solid modelling and 3-D tools. With the release of AutoCAD 2007 improved 3D modelling saw the light, which means better navigation when working in three dimensions. It also became easier to edit 3-D models. The mental ray engine was included in rendering and thus it was now possible to do quality renderings. AutoCAD 2010 introduced parametric functionality and network modelling. At this moment, AutoCAD only runs under Microsoft Windows operating systems. It is available in 32-bit and 64-bit versions. AutoCAD can run on an emulator or compatibility layer like VM-ware Workstation or Wine, although various performance issues can arise if you work with 3-D objects or large drawings.

Choosing a system that works for you depends solely on the type of work you want to do. Many experts say that SolidWorks is more effective when working on 3 dimensional designs and that AutoCAD is the way to go for 2 dimensional design.