Both whey protein and casein protein promote muscle growth. Casein is popularly known as a night protein, as it is extremely slow digesting protein. It isn’t a meal replacement, but it is mostly consumed at night, as the last meal of the day. It promotes muscle growth during the resting and recovery period. 

Whey protein is consumed as a post workout meal, and is optimal for muscle recovery . Both the whey, as well as casein have their own qualities. And both are good for muscle growth. 

Both the same protein and the way protein are derived from milk, but they have distinctive differences and different benefits. The differences are majorly in terms of the digestion,, the benefits and the  usage. Whether you want to use a whey protein or a casein protein, it is dependant on your fitness goals and dietary requirements. 

Whey  Protein is a fast digesting protein which is rapidly absorbed by the body and it is extracted from the  watery substance that separates during the cheese production. It is rich in branch chain amino acids, especially in Isolucine Lucine and Valine. There are different types of whey protein. The whey protein concentrate, whey protein  isolate and hydrolysed whey. All of them differ in the purity and the amount of percentage of protein , and in their digestibility. An isolate is generally chosen by the beginners and as and when their fitness goals become a little advanced, then they go in for isolate or hydrolysed. 

CASIEN  is a slow digesting protein that forms like a gel like substance in the stomach and it has very slow absorption. It provides steady release of amino in the blood stream, typically for a period of 7 to 8 hours. It is for this reason that it is known as a night  Protein. Casein Protein is best taken before bed as it provides your muscles with a constant supply of protein eating in muscle recovery and growth overnight. It also gives you a feeling of satiety and it is thicker and creamier.