What's the difference between a max bid and a pre bid?

Before an auction goes live, there is always the opportunity to place a so-called advance bid on all items. This is a binding bid and will be displayed in its total amount when the auction starts.

Maximum bids are the bids you place when the auction has gone live and mean that you enter the maximum price you want to pay for the item and let your bid be automatically increased according to the bid increase step if another bidder chooses to place a higher bid. This happens until your maximum bid is reached.