The principle difference between the salt marshes and mangrove forest does not lies in terms of salinity of water because they both share the same habitat.
They both grown in the halophytic conditions which means the salt concentration is very high.
The mangroves grown near the coastal area and serves as the home for many different kinds of organisms and also serves as the best plant that prevents erosion.
Salt marshes are coastal wetlands found throughout the world on protected shorelines and on the edges of estuaries where freshwater mixes with seawater. [ Mangrove forests are those which contain Mangroves which are trees and shrubs that grow in saline (brackish) coastal habitats in the tropics and subtropics. ] SO TRUE
During the process of photosynthesis the plant would use carbon dioxide, sunlight and water in order to produce and release sugar and oxygen back into the air.