Worms seem to be the greatest promoters of vegetation, which would proceed but lamely without them, by boring, perforating, and loosening the soil, and rendering it pervious to rains and fibres of plants, by drawing straws and stalks of leaves and twigs into it; most of all, by throwing up such infinite numbers of lumps of earth, the worm-casts, being their excrement is the fine manure for grain and grass.” – Charles Darwin (The Action of Worms)
Vermicast (worm castings) is the material deposited by the earthworms after the material passes through the digestive tracj of the worm (worm manure).
Vermicompost (worm compost) contains some earthworm castings, it also contains droppings from the multitude of other creatures that call your compost its home, plus bits and organic matter in various stages of decomposition.
The African night crawler is the most efficient worm waste converter. It also produces substances beneficial to plants.