People are not in this world all alone. Animals are here too. Some of these animals share our homes, others keep as far away from people as they can. What's the difference?
Animals that depend on people to look after them are called domestic animals. People have trained and bred them over the centuries to be tame and useful to people. Most domestic animals cannot survive in the wild because they have lost the ability to look after themselves. Modern cattle, pigs or dogs wouldn't last for long if turned out to make it on their own. They are genetically different from their wild ancestors.
Feral is the word used to describe the few domestic animals that do survive long enough to become "wild" again. Feral animals are animals that were once domestic, or their offspring. "Wild" horses are actually feral horses.
Wild animals have developed as nature intended them to. The traits that have passed from generation to generation are those that allowed them to survive, not those that made them useful to humans. Those survival instincts make it very hard, if not impossible, for people to handle them safely and any handling causes lots of stress. Wild animals are perfectly adapted to living in their habitat and are capable of finding their own food, water and shelter as long as humans don't interfere. Some wild animals have adapted to living very close to people; others stay far away.
Remember that if you come across a wild animal, you need to leave it alone. Wild animals never make good pets. Also, domestic animals such as pets should never be released into the wild to look after themselves.