There is no difference. In Massachusetts, the specific criminal legal statute refers to "Operating Under the Influence of Intoxicating Liquor", or OUI for short.Different state laws call the same act "Driving Under the Influence" (DUI) or "Driving While Intoxicated" (DWI), but they all essentially mean the same thing: a drunk driving accusation and charge. And some states do differentiate between the two, or classify a DWI as a lesser offense from a DUI.But again, none of that applies in Massachusetts, it is all the same.For most people, DUI is the most commonly used abbreviation, but courts refer to them technically as an "OUI-Liquor".