The largest are probably mobile betting and allowing for instant credit card deposits.
There is also the fantasy of being able to win money but the reality that if you actually win money in a consistent fashion, you will be either kicked-off or your action will be severely crippled.
I'd like to think the emerging prediction markets, like Polymarket, are much fairer systems, especially for winning players, and would be much better than sports books like DraftKings, FanDuel, etc.
Not to mention the Pandora's box that prediction markets open, when the order book can begin to influence real life events - from match fixing, to assassination markets.