Drinnking milk insted of taking casein protein?

well for the past few days i have been taking casein protein (muscle milk) before i go to bed, but i was reading online, and was like o snap casien protein is milk protein, so if i drink 2 gles of milk before bed, will it be better then taking this protein, will it be cheeper, healthier, it would be skim milk and yes im lifting alot