You can divide protein into fast proteins and slow proteins. Generally, we consider whey protein to be fast proteins. A whey hydrolysate for instance, gets almost immediately absorbed by the body. Casein protein or milk protein are considered slow proteins. A quality of casein protein is that it slowly releases amino acids and will keep you sated for longer than a whey shake will. That is why casein protein shakes are perfect during the night.
Regular whey protein are known to be suitable for breakfast or surrounding workouts. If you are looking for a protein for nighttime, a casein protein is what you are looking for. This is the biggest difference between Night protein, Casein protein, and other forms of whey protein.