Once the whistle goes, "live betting vs pre match" comes down to timing. Live betting means placing a bet after the game has started, while the result is still open. In play betting and in game betting are other names for the same thing. What does it change? The odds move with every goal, point or turn of play, the markets open and close within seconds, and the bettor reacts to what is happening instead of guessing in advance.
Live betting odds work from the same idea as any other price: the book estimates the chance of each outcome and keeps a margin on top. The difference is time. Before the game the chance rests on form and team news; in play it rests on the score, the minutes left and the flow of the match. Prices can swing hard, and the margin on live markets is usually wider than on the pre match line.
How does live betting work behind the screen? A trading team and a data feed follow the event, and a pricing model updates the odds after each action. When something important happens, such as a goal, a penalty or a break of serve, the market is suspended for a moment and reopens at new prices. Bets placed during a suspension are refused, so the slip often asks the bettor to confirm the new price.
A data feed and a pricing model update the odds after every action, so each goal, point or turn of play produces a new price.
Impulse: a lost bet invites another straight away, and the speed of the market makes chasing losses easy to slip into.
A stream reaches the viewer a few seconds after the book's data feed reports the action, so the price has often moved already.
Usually yes. Live markets tend to carry a wider margin than the line set before kickoff, on top of prices that swing hard.