Jungle draft is when you have boosters from many different sets instead of each player having same set of boosters, for maximal fun have different boosters for all players so no booster is repeated.
This takes down the chance for people to study the cards of the set and play knowing the format as there is so many different sets that it would be difficult to study the sets to know what is going to happen and which cards are going to be in these boosters.
read more:
https://mtg.gamepedia.com/Pick-a-Pack
What would be your favorite 3 boosters to open in a jungle draft?
MTG blog 