How does a swamp differ from a marsh

A swamp has an exess in trees and stuff where as a marsh doesn't

Swamp is a place where the plants that make up the area covered in water are primarily woody plants or trees. Woody plants would be mangroves or cypress trees. A marsh, on the other hand, is defined as having no woody plants. The non-woody plants would be saltmarsh grasses, reeds, or sedges.