The stock obviously has three settings. Intermittent, low constant, and high constant, and of course the "mist" feature for a one-time wipe. The variable intermittent stalk is what you are used to seeing in american cars, it has the dial to decide how fast the "intermittent" (wipe and then pause) setting goes. And it, too has the slow and fast constant. So the variable offers you more control. Just think of all Chevy and Ford products, most of them have the dial or knob on the stalk that controls the intermittent speed.
FYI, you can take the variable stalk off of any Mazda MPV and slap it right on. You can also buy the part from Mazda, and most likely from a parts store (using the MPV part). It installs right in, quick job, do-it-yourselfer.
