How is pasteurization different from sterilization?
Basically, pasteurization is a process that kills most bacteria. Sous vide is a method that you can use to pasteurize food (eggs for example) which will kill most, but not all, bacteria. Sterilization is a method of killing all bacteria (e.g. by irradiation or heat). Sterilization would be what you'd want to use for canning, for example. 

Milk is pasteurized by the manufacturer and can use lower heat for a longer period or higher heat for a shorter period.