The packaging aspect is not much to say, the difference is not really very big, mainly depends on the sterilization method.
Milk usually has two methods of sterilization, one is pasteurization, one is ultra-high temperature sterilization.
The characteristics of pasteurization: in killing harmful bacteria at the same time, will not destroy the nutrition of milk, but after a period of time will breed new bacteria, so the shelf life time is short, and need to be put in the refrigerator.
Features of ultra-high-temperature sterilization: sterilization is thorough, bacteria are not easy to breed, so the shelf life is long, can be stored at room temperature, but the disadvantage is that it destroys the nutrition and taste of milk.
If you are focusing on the nutrition of milk, be sure to buy pasteurized milk, nowadays the milk packaging will usually have a note on whether it is pasteurized or ultra-high temperature sterilization. Shelf life of 8 months of milk is definitely ultra-high temperature sterilization, nutrition are destroyed, for the family, there is really no need to buy it, this kind of milk is also suitable for the catering industry with milk as an ingredient. Pasteurized milk shelf life in China I heard that 7 days, but I've seen more than ten days abroad, I guess the foreign technology is still more advanced than the domestic. Domestic milk with a shelf life of one month is certainly also ultra-high temperature sterilization, but I guess it is better than the shelf life of 8 months.
In short, when you buy milk, look at the packaging, it says pasteurization, or ultra-high temperature sterilization.