The distinction between a barrier island and a sea island is:
◦ barrier islands are transient depositional features whereas sea islands have bedrock foundations.
◦ barrier islands are typical of secondary coasts where biological processes modify the original coastline and sea islands are more of a feature associated with primary coasts.
◦ barrier islands are erosional coastal features whereas sea islands are depositional coastal features.
◦ barrier islands are most common on the west coast of the U.S, in contrast to sea islands which are common on the west and east coast of the U.S.
◦ barrier islands are less affected by storm surge and erosion in a storm than sea islands.