When going all the way to Saturn you need to be really choosy about your equipment. A regular camera would break down in the radiation-filled vacuum of space so a special camera is needed. One that can survive for decades in space functioning perfectly, continuously.

Now as to the optics - all consumer cameras are effectively the same. All CCDs capture light the same way by using color filters to get distinct values for red green and blue. The difference is your camera already does all that post-processing using an onboard computer to convert RAW files to JPEGs using some algorithms that make a "best guess" at the colors (or, if you shoot RAW, play with all the color settings in a processing program like Photoshop to see just how hard it is to define "true color").

The Imaging Science Subsystem on Cassini is a science instrument first and an imaging device second. To do real science on the data it collects the instrument needs to be finely calibrated and we need to know exactly how it works and what its systematic errors are. Furthermore, by having independent filter wheels we can do more than just the old red/green/blue. By adding filters for near UV and near IR light we can see more than the human eye can - and this can lead to some dazzling results.

Case in point: Titan. Titan is Saturn's largest moon and is shrouded in a thick orange haze that's denser than our atmosphere on Earth. Here is how Titan looks in "true color". But look at Titan in the near IR part of the spectrum and BAM! All kinds of amazing topology.

Voyager didn't have the right kind of instrumentation for looking underneath Titan's hazes. You could say that its imaging device was closer to a "normal" camera. When we went back with Cassini we went prepared to see much more than we've ever seen before - more than human eyes are capable.