I'm not sure specifically who the four friends are without knowing the exact story. They could be animals like a fox, a rabbit, a deer and a bird, often in such moral stories animals are used to represent different characters.
In many 'four friends moral stories', the friends could be a combination of characters. It could be a young adventurer, an old wise man, a brave warrior and a kind-hearted healer. They might embark on a journey together, facing all sorts of perils. Their different personalities and abilities play important roles in the story, but again, it really depends on the specific 'four friends moral story'.
There are various possibilities for the four friends in the story. They might be four people from different backgrounds, for example, a farmer, a scholar, a merchant and a craftsman. Each with their own way of life and skills, and through their friendship, they learn from each other and grow. However, this is just a speculation without more details about the 'four friends moral story'.