ColorMunki Create is the suite's entry-level product. It comes with a USB bus-powered colorimeter that is used to calibrate your monitor along with the ColorMunki Create software.
Create allows you to compose sets of colours (palettes) that you can then export to other desktop software, like Illustrator and Photoshop, to help maintain consistency across applications. You can create these palettes in an assortment of ways: you can enter your own colour values; select from various Pantone colour libraries; create harmonious sets automatically; or auto-extract a colour set from an image. The last option is particularly fun and useful, giving the designer a set of colours based on those most predominant in a source image. Matching other colours in a design to an image or using one of the image's colours to find other harmonious colours gives designers a nice set of tools for exploring the colour potential in their work.
In Create, monitor profiling is straightforward. The software instructs you to place the device on the screen, push one button, and you're off to the races. The process is automatic and requires no user intervention. After about two minutes, you've got a profile that is specifically tailored to your monitor. Since monitors change or drift over time (CRTs are notoriously worse than LCDs and LEDs) the software can remind you to re-calibrate at a given interval. Once a month is probably OK for most users.
ColorMunki Design is the step up from Create, and aimed, as its name implies, at designers. It includes software with the same functionality as Create, as well as plug-ins for various desktop publishing applications, called AppSet, to keep palettes and colour settings in sync across them. On the hardware side, it includes a USB bus-powered spectrophotometer instead of a monitor calibrator. A spectrophotometer can read colours from emissive sources, like your monitor, as well as from reflective material, allowing you to 'digitize' colours from objects, fabric, or printed material. So, along with profiling your monitor's colour reproduction, you can also profile your printers.
Like monitor profiling, the printer profiling process is very simple. You print out a sheet of colored stripes and scan them with the ColorMunki device. The software then processes them and prints a second 'tune-up' sheet that is measured using the spectrophotometer to refine the profile's calibration, and you're done--at least for that printer and paper combination. You'll want to re-calibrate if you switch printers or papers. We calibrated the Xerox printer to standard copy paper and the Canon to glossy and matte photo paper. Purists will want to calibrate whenever an ink tank is changed, but that's not absolutely necessary for the casual user.
This profiling process creates a set of ICC (International Colour Consortium) profiles that are used by both Mac OS X, via ColorSync, and by graphics and design applications, like those in Adobe Creative Suite, to communicate the colour reproducing abilities of the hardware in your system. Now, you have a calibrated system, ostensibly providing consistency between what you see on the monitor and what the printer outputs.