Not exactly. In ordinary 120v home wiring there is a a hot, neutral, and ground - modern receptacles are polarized with the neutral (white) wire being attached to the silver screw (the long slot on the receptacle,) and the hot wire being attached to the brass screw (short slot. Ground goes to green screw of course.) I know that on #16 lampwire the ridged side is normally seen as being the neutral wire. Most of this small stuff does not look to have the wires marked in any way, or at least not that I can see from photos. It may be more obvious in person. I do know that I've a few tools with plugs where both blades are the same width so I assume there are instances where it does not matter and was wondering if these might be one of those instances. Ordinarily if the polarity is not correct, there could still be current flowing to the device even if it's switched off.