There is no question that Microsoft Visio and Adobe Illustrator are both great applications. And when it comes to drawing vector based diagrams, both applications can be used to produce great results. Often times however, it can be tempting to use one application and then discover that the other is more appropriate. So here are some things to consider before you put mouse to virtual paper in one of these applications.
Microsoft Visio is an application designed from the ground up to create diagrams. It features a vast library of shapes and there is no question that one of its greatest features is the quick connectors between shapes which remain connected as objects are moved around. Other strengths include full integration into other MS Office documents (which means you will likely find Visio pre-installed on most enterprise desktops), the ability to add dynamic behaviour thru VBA scripting, and quick access to formatting options like line styles, fill colors etc.
Where Visio starts to breakdown is in the creation of more graphically intense diagrams. Its handling of graphics is mediocre at best because it lacks basic image processing capabilities such as handling transparent colors. Shape creation is also limited to basic 2D shapes and while its formatting options are easily accessible, they are also very “cookie cutter”. For example you can easily add a drop shadow to a line, but have limited control over its appearance.
On the other side of the coin sits Adobe Illustrator. While there is no question that Illustrator was designed as a general purpose drawing package, it’s still very capable of producing diagrams. Unlike Visio it does not feature a library of shapes nor does it have quick connections between objects. This means that creating the equivalent of a Visio diagram in Illustrator, will generally take much longer. It’s also much more difficult for new users to pick up and learn, and is not likely installed on everyone’s desktop.
However Illustrator picks up where Visio leaves off. It allows for the creation of beautiful, graphically intense diagrams to be created with ease. Not only that, but complex diagrams can be easily managed with features like Layers, whereby objects can be locked and optionally hidden so that other parts of the diagram can be edited in isolation. While objects must be drawn by hand, you do have complete control over their complexity and how they look as they’re transformed (ie: scaled). Basic objects can also be given a 3D appearance, while control over colors and gradients is second to none including support for CMYK. More generally, it’s easy to create very professional looking diagrams.
While this comparison does not even begin to scratch the surface of either application, I believe it provides enough clues as to which application you should select for creating your diagram.
Generally speaking Visio is best suited for diagrams showing connections between simple objects. Diagrams like flow charts, entity relationships etc. are quick and easy to create as long as the shapes representing the entities remain simple and you don’t require an overly pretty end result.
For diagrams that must look their best, Illustrator is the only choice even if the diagrams involve connections between objects. Illustrator’s lack of quick connectors is more than made up by its limitless drawing capabilities and object management features such as Layers. However be prepared to spend some time learning how Illustrator works before diving in.