How does a tropical storm differ from a hurricane?
Tropical storms and hurricanes (and typhoons) are huge tropical depressions (low pressure centers). The lower the pressure at the center (in relation to the air around it) the greater the pressure gradient. The greater a pressure gradient becomes the higher the wind speed. When the pressure gradient of the tropical depression produces winds of 35 knots, we categorize it as a tropical storm. When the pressure gradient of a tropic storm becomes great enough to produce wind speeds of 64 knots (don't ask me why 64 and not 65), we classify it as a hurricane.
I hope that answers your question.