distinguish between saprotrophs and decomposers
Saprotrophs are the organisms that derive their nourishment from dead and decayed organisms. For example: mushroom.
Decomposers are the organisms that consume dead organisms and break them down into simple chemical components like carbon, nitrogen and other nutrients which are essential for living organisms. By eating up the dead matters they clean the environment. Without decomposers the world would have filled with dead bodies of plants and animals. Therefore, decomposers are called nature's cleansers.
Detritivores are a type of heterotrophs that feed on the dead or organic biomass including animals, plants, and faeces. Detritivores are essentially able to digest lumps of biomass separately; hence, most of the unicellular organisms (bacteria and protozoa) and fungi may not fall into the category of detritivores. However, detritivores should not be confused with decomposers and scavengers. Detritivores in aquatic environments are usually called the bottom feeders; polychaetes, fiddler crabs, sea star, sea cucumber, and some Terebellids are common examples. Earthworm is a classic example of terrestrial detritivores, but slugs, woodlice, dung flies, millipedes, and most of the worms are some of the other examples.
Saprotrophs are heterotrophic organisms that feed on decaying or dead plant matter in the presence of adequate levels of water, oxygen, pH, and temperature. Fungi species predominate among saprotrophs due to their ability to digest lignin in the xylem tissues of plants. There is an interesting instance where most of the dead plants during the carboniferous period did not undergo decomposition because the saprotrophs had not developed the lignin digesting enzymes by then; hence, those large plant deposits became available for the present day consumption as fossil fuels.