While bulkheads and seawalls both retain soil and help to prevent the erosion of the land behind them, the main difference between these two structures is their ability to provide protection from waves. Although bulkheads can provide minimal protection from waves, this is not their main function. Seawalls are designed to be used on beaches where wave activity is high. Bulkheads are more commonly found in bays, marinas, ports, rivers and lakes.