Nitrogen bubbles by themselves CANNOT be caused by an embolism. A rough and dirty explanation of an embolism is as follows: the gas in your lungs is forced out of the lungs into your bloodstream, usually caused by an injury to the lungs*.
The point though is that the gas you are breathing exits your lungs. If you are breathing air and it enters your bloodstream the bubbles will thus be O2 and N2 bubbles; if you are breathing trimix it will be O2, N2 and He bubbles and so forth.
If you get only N2 bubbles in the bloodstream that would be caused by DCS (the bends). With DCS the O2 in your blood has had the chance to be metabolised so it can't be present to form bubbles.
Its not sloppy speaking, its sloppy causality. N2 bubbles by themselves can't be caused by an embolism, they would be accompanied by other gases..
If you wanted to get a nitrogen embolism you would have to be breathing pure N2. *blink*
Spot on! They might have some of the same symptoms and sometimes have the same results (bubbles in the bloodstream) but they are caused by two different things.
*note an embolism is actually any foreign body in the bloodstream, a blood clot, a piece of fatty tissue, your mother's micro-sized hairbrush ... anything. But in diving an embolism is shorthand for Arterial Gas Embolism (AGE) which refers to gas in the bloodstream.