Understanding Japan’s system for classifying typhoons can be a challenge. For one, it differs from that used for hurricanes, and there are also differences in how the storms are discussed in English versus Japanese.

As Typhoon Shanshan — which as of Friday became Tropical Storm Shanshan — moves toward Shikoku, it marks a good time to brush up on the terminology.

When checking the news about typhoons in Japan, you may see comparisons to hurricane categories. But what’s the difference exactly between a hurricane and a typhoon? Essentially, a hurricane and typhoon are the same weather phenomenon — a tropical cyclone. These cyclones form under specific conditions: a preexisting weather disturbance, warm tropical oceans, abundant moisture and relatively light winds.