Culturing of earthworms is known as vermiculture. It goals at increasing the growth of earthworms so as to get help in producing manure. Vermiculture either help to expand vermicomposting operation or for direct sale to customers.
Whereas,
Composting process of using various species of worms like red wigglers, white worms or other earthworms to create a compost known as worm casting from decomposed vegetables, food waste, bedding material etc. is known as vermicompost manure. This is organic vermicompost manure. These two procedure seems similar but are different.
If your want to produce vermi compost, you need to have your maximum worm population density all of the time. If your goal is to produce worms, you need to keep the population density low enough that reproductive rates are optimized. Vermiculture process is a part of vermicomposting process.