it all depends on the ecosystem cuz An area can be saturated (soaked) with water which makes it a Wetland, and it can be located where a freshwater river or stream merges with an ocean which makes it an Estuary. The definition of Estuary is the tidal mouth of a large river, where the tide meets the stream; and the definition of Wetland is a land consisting of marshes or swamps; saturated land.
hope this helps u out......good luck to you