Auction leagues are private leagues for small groups of users. Each user is given a budget of fire tokens, which they can use to bid on players. The user who bids the highest for a player claims that player for their tribe. You might decide to spend all of your money to bid high on your favorite contender, or scoop up a large number of players who are going for cheap prices.
A Draft league is for small groups of users. Each participant drafts a tribe of players. Players earn points based on their performance in the season. The tribe with the most total points at the end of the season wins!