That's quite the question you have there, faceless amalgam of friends, family, clients, and random people who stop me on the street and in the courthouse while I'm wearing a suit. I suppose there are two different ways to answer that question, depending on what you're really asking.

What does it mean that I'm charged with "OWI" instead of "DUI" or "DWI"?

It means that you were charged in the State of Wisconsin. Wisconsin uses the phrase "Operating While Intoxicated" instead of "Driving While Intoxicated" or "Driving Under the Influence," so anyone who says they were arrested for "DUI" within the borders of the state is not using the correct legal term. If a lawyer uses the wrong term with you, correct the lawyer; he or she will respect you more for it and will stop talking down to you. If a friend uses the wrong term with you, never speak to them again.

What does it mean that Wisconsin uses of "OWI" instead of "DUI" or "DWI"?

Now we're talking. There is a difference between "driving" a vehicle and "operating" a vehicle. According to the statute, "'Drive' means the exercise of physical control over the speed and direction of a motor vehicle while it is in motion," and "'Operate' means the physical manipulation or activation of any of the controls of a motor vehicle necessary to put it in motion."

Under these definitions, then, you can't "drive" a vehicle that isn't moving, but you can definitely "operate" one. Turning the ignition? You aren't exercising physical control over the speed and direction of the vehicle (yet), but you are activating one of the controls necessary to put it in motion. As the Wisconsin Court of Appeals put it in Milwaukee County v. Proegler,

The prohibition against the "activation of any of the controls of a motor vehicle necessary to put it in motion" applies either to turning on the ignition or leaving the motor running while the vehicle is in "park." One who enters a vehicle while intoxicated, and does nothing more than start the engine is as much of a threat to himself and the public as one who actually drives while intoxicated. The hazard always exists that the car may be caused to move accidentally, or that the one who starts the car may decide to drive it.

You may be tempted to say, "But Officer, I was just sitting in the driver's seat! My friend started it for me! I was just staying warm!" Shut up! Don't say anything! Ask to speak to your attorney! You'll convince a jury you didn't operate the vehicle before you convince the officer of that, but if you (by which I mean "you and your attorney") can convince the jury of that then you should be acquitted, like the defendant in Village of Cross Plains v. Haanstad:

According to the explicit words of the statute, in order to "operate" a motor vehicle, the statute requires that the person physically manipulate or activate any of the controls of the motor vehicle necessary to put it in motion. The Village does not dispute, and the court of appeals concluded, that Haanstad never physically manipulated or activated any of the vehicle's controls. She did not turn on or turn off the ignition of the car. She did not touch the ignition key, the gas pedal, the brake, or any other controls of the vehicle. Haanstad simply sat in the driver's seat with her feet and body pointed towards the passenger seat. Haanstad did not "operate" a motor vehicle under the statute's plain meaning.

PRO TIP: It helps if you can remember your friend's name and phone number. Your attorney will want that information. Don't underestimate the power of circumstantial evidence suggesting you operated the vehicle.

None of these distinctions matter, of course, in most OWI/DUI/DWI cases, since most begin with a police officer conducting a traffic stop and seeing the eventual arrestee behind the wheel. "Driving" counts as "operating," obviously. In conclusion, don't drink and operate, folks.