For questions related to diets that restrict use of animal products.
People and medical studies usually refer to:
Vegetarianism or ovo-lacto vegetarianism as the diet that excludes meat (red meat, poultry, seafood and the flesh of any other animal), but includes both eggs and dairy products.
Veganism or strict vegetarianism as the diet that excludes all animal products as meat, milk, dairy, eggs, honey. Thus veganism is one of the possible vegetarian diets.
People choose to follow a vegetarian diets for many different kinds of reasons: ethics, health, environmental sustainability, social justice, cheapness, religious beliefs, aesthetics, etc.