According to the National Oceanographic and Atmospheric Administration, a hurricane is a cyclonic storm that forms over tropical or subtropical waters and has sustained wind speeds of at least 74 mph, while a tsunami is a tidal wave created by an earthquake or underwater volcano. Hurricanes and tidal waves both can be extremely dangerous to those living near the coastline.
Hurricanes occur when warm, calm ocean waters create convection air currents. As warm air rises, it creates a zone of low pressure, drawing in more air from outside areas. This motion carries moisture into the atmosphere, creating high level clouds and causing them to rotate. If the storm remains over warm water long enough, its winds may reach 74 miles per hour, at which point it becomes a hurricane. Hurricanes can push ocean water ahead of them, creating storm surges and dangerous waves, but these are markedly different from tsunamis.
A tsunami occurs when an earthquake or volcanic eruption creates a shockwave on the ocean's surface. This wave may only be a few feet high in the deep ocean, but its energy and height can increase as the storm travels into shallower water. Depending on the waveform, water may actually retreat from the shoreline before the tsunami strikes land for the first time.