How are they different? Decomposers - They convert complex molecules into simpler ones. Digestion (by heterotrophs) at any level does it, so why decomposers, another term then? Detrivores - They consume (engulf) dead1 and decaying (means already broken down? well what is that then?2) matter. Savengers- They consume dead organisms (plants and animals). 1. savengers also consume dead organism 2 Decaying matter must mean that some organic matter has been broken down into simpler molecules on which they are feeding-what's the source of these simple molecules? If I recall correctly the word decomposition is also associated with faeces.