The natural yoghurt acidifies quickly and thus gets the typical taste while bifido yoghurt is more mildly acidifying and also contains bifidobacterium.
Bifidobacteria are one of the main components of our intestinal flora (approx. 25 %). Just like the lactic acid bacteria, they process sugar into lactic acid. That is why they are a popular candidate in yoghurt cultures. Bifidobacteria have a controlling role in the intestinal flora. This is because they produce the toxin "bifidin" and can thus prevent the multiplication of intestinal bacteria that are harmful to health.