Because not all snowfalls look alike, forecasters use different terms to describe the rate and duration of falling snow. Let me mention the most common:

A snow squall is a heavy, brief burst of snow that can put down a quick inch or two. A snow shower is a moderate, but again brief, period of snow, which sometimes gives a light accumulation. Snow flurries describe a very light and brief snow shower, with no measurable accumulation. Notice that each of these terms has the word "brief" in its definition: they all describe snows that don't last long.

Steadier snows that last, say for at least a few hours - are categorized as either light, moderate, or heavy, depending on the visibility: It's light snow if you can see more than half a mile, moderate snow if visibility is between one-quarter and one-half a mile, and heavy snow if visibility is one-quarter of a mile or less.

So there IS a method behind all that snow terminology you hear!