First, you need to understand that fermented milk products are made from milk and carry, first of all, all the benefits of milk. Therefore, saying that it is more useful is not entirely true. The main benefit of milk and fermented milk products is the presence of complete animal protein, which is a building material for our body, and calcium, which is necessary to maintain the density of bones and enamel of teeth, as well as for the work of the muscular, cardiovascular, and nervous systems. Fermented milk products differ from milk in that during the production process milk is fermented by the action of lactic acid bacteria. For example, two lactic acid bacteria are used for the production of yoghurts - Bulgarian lactic acid bacillus and Thermophilic streptococcus. These bacteria ferment milk, making it more easily digestible, because in the process of lactic acid fermentation, milk protein and milk sugar - lactose, are partially broken down, calcium becomes acidic, which makes it more accessible for assimilation.
If you explain it on your fingers, then fermented milk products are already often digested milk. Accordingly, many difficult-to-digest components are easier to digest.