Numbers after a draft format
You must be referring to MTGO (the online version of the game). You generally enter a draft with seven other players (for a total of eight). The postfix refers to how many packs you will receive when the tournament is over.

The postfix "6-2-2-2" indicates three rounds of Swiss. Swiss means that you will continue to play whether you win or lose. After three rounds of 6-2-2-2 are completed:


One player will have three wins. That player receives six packs.
Three players will have two wins. They will each receive two packs.


The postfix "8-4" indicates three rounds of single elimination. This means that when you lose, you are out. After three rounds of 8-4 are completed:


One player will be the winner. That player receives eight packs.
One player will be the runner-up. That player receives four packs.


This is described in more detail on the Wizards of the Coast website (which I just noticed you also linked to in the question).