A Wind Gust is generally is some very strong winds that blow in a sweeping motion. They will sweep away anything in their paths and usually a strong wind gust might cause a considerable amount of damage to home, cars and the environment. Wind gusts will not last for a long time; they will go as quick as they come. 
Wind is created by changes in temperature and pressure. Winds mostly blow from high pressure systems toward low pressure systems. When the wind gets over the average wind speed (7-10 mph) it is said that the wind is a gust.

Sea breezes are different. They are created when the cooler air from the water blows into the land, which is usually warmer than the sea.